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Lab assistant interview questions, and how to answer them

A lab assistant interview is mostly a test of whether you'll follow the procedure when nobody's watching. Supervisors aren't hunting for brilliance. They want to hear that you'll stop and ask before you guess, that blood doesn't bother you, and that you'll turn up for the shift you agreed to. The best preparation is walking through a few real bench situations out loud, because most of the questions are exactly that: something went wrong, what do you do.

12 questions7 minute read

Part 1

1.A tube arrives with a label that doesn't match the requisition. What do you do?

Why they ask

Specimen identification is the single thing a lab assistant can get most badly wrong. They want to hear that you won't fix it yourself.

How to answer

  • Don't process it and don't relabel it on your own
  • Set it aside in the problem area and document it the way the lab's procedure says
  • Tell the lead tech and follow the rejection or recollection process
  • Mention that the patient may need a redraw, and that's still better than a wrong result

2.Walk me through how you'd process a batch of blood specimens from a courier drop.

Why they ask

It shows whether you understand the order of the work: check, receive, spin, split, route. Supervisors listen for whether you check identity before anything touches a machine.

How to answer

  • Check the manifest against what's actually in the bag, including temperature requirements
  • Receive each specimen in the LIS and label it
  • Let serum tubes clot before spinning, and balance the centrifuge
  • Aliquot where needed and route tubes to the right department or storage

3.What would you do if a tube broke inside the centrifuge?

Why they ask

Aerosols from a broken tube are a real exposure risk, and panicking makes it worse.

How to answer

  • Turn it off and leave the lid closed for a while so aerosols can settle
  • Put on gloves and other PPE before opening it
  • Clean up with the lab's disinfectant and dispose of glass in a sharps container
  • Report it and let the tech know which specimen needs recollecting
4.How do you prepare a solution or reagent from a written recipe?

Why they ask

Media and reagent prep is half the job in many research and micro labs, and small errors spoil whole batches.

How to answer

  • Read the SDS and the full procedure before starting
  • Use a calibrated balance and the right glassware, and check units twice
  • Label with contents, concentration, your initials, prep date and expiration
  • Log lot numbers so the batch can be traced if something fails
5.How comfortable are you around blood, urine and other specimens?

Why they ask

Some new hires quit in the first week over it. They'd rather know now.

How to answer

  • Give a straight answer and a real example of when you've handled it
  • Show you know the precautions: gloves, coat, eye protection, no food at the bench
  • Mention your bloodborne pathogens training if you've had it

Part 2

6.A stat specimen comes in while you're halfway through a large routine batch. What happens next?

Why they ask

Prioritizing without losing track of the batch is the everyday skill of a processing bench.

How to answer

  • Stat goes first, so pause the routine work at a safe stopping point
  • Mark where you stopped so nothing gets received twice or skipped
  • Process and deliver the stat, then tell the tech it's on its way
  • Go back to the batch and double-check the last few tubes
7.What's aseptic technique, and when do you use it?

Why they ask

Research and microbiology labs need to know you won't contaminate cultures or media.

How to answer

  • Working in a way that keeps microbes out of sterile materials
  • Examples: working near a flame or in a biosafety cabinet, not touching sterile surfaces, flaming loops
  • Use it for pouring plates, transferring cultures and handling sterile media
8.A reference lab needs a frozen specimen sent out today. How would you package it?

Why they ask

Send-outs to reference labs are a routine assistant task, and a thawed or leaking package means the patient gets redrawn and the test starts over.

How to answer

  • Check the reference lab's test directory for the specimen type, volume and temperature it needs
  • Use leak-proof primary and secondary containers with absorbent material between them
  • Pack enough dry ice for the trip and label the box for dry ice and biological substances
  • Fill out the requisition and manifest, and log the tracking number so the tech can follow it
  • Mention that shipping dangerous goods needs specific training, and that you'd ask if you hadn't had it
9.How do you keep a lab stocked without over-ordering?

Why they ask

Running out of tubes or pipette tips can stop the lab, and expired reagents waste money. In a small lab, the assistant is often the only person who notices a shelf running low until it's empty.

How to answer

  • Keep a simple par-level sheet or use the lab's inventory system
  • Rotate stock so the oldest lot is used first
  • Flag anything close to expiring and tell whoever orders
10.Tell me about a time you made a mistake at work and how you handled it.

Why they ask

Labs rely on people reporting their own errors quickly. Hiding one is worse than making it.

How to answer

  • Pick a real, small mistake, not a disguised strength
  • Say how you found it and who you told
  • Explain what you changed so it didn't happen again

Part 3

11.This role is evenings and some weekends. How does that fit your life?

Why they ask

Night and weekend benches are the hardest to staff, and no-shows hurt the whole lab.

How to answer

  • Be honest about what you can commit to
  • If it fits, say how you've handled similar shifts before
  • Ask how shift bids or rotations work so you know what you're agreeing to
12.Why do you want to work in a lab?

Why they ask

They want to know if you'll stay or if this is a stopgap you'll leave soon.

How to answer

  • Say what draws you to the work itself: accuracy, routine, being part of patient care or research
  • If you're aiming for a technician program, say so, and frame this job as the base for it
  • Tie it to something specific you saw in their lab or posting

Questions to ask them

Ask at least two. It shows you're picking them too.

  • What does a normal shift on the processing bench look like, and where does it usually back up?
  • How long is training before I'm working the bench on my own?
  • Which departments would I rotate through, and would I ever help with phlebotomy?
  • Does the lab support assistants who want to go back to school for a technician program?
  • What mistakes do new assistants tend to make, and how do you catch them?

Related interview guides

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