Which Science Classes Should You Retake for CRNA School?

Updated August 2026

Retake a core science if you earned a B- or lower, or if the class is more than 5 years old. Aim for an A or A-. And take the harder course in that subject rather than repeating the same one, because it signals more.

If you're going to retake a science class for CRNA school, the question isn't really whether a retake helps. It's which course, at what level, and what grade you need to make the semester worth it. I teach this as a decision rule in the membership because "should I retake chemistry?" has a real answer once you know two things: the grade you earned and how old the class is.

Here's the rule I use.

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Retaking Science Classes

The full lesson: the retake decision table, how to level up within each subject, and how to build a retake schedule around lab availability and application deadlines.

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When should you retake a science prerequisite?

Two triggers matter. A low grade, or an old class. Find your row:

Core sciences means chemistry, anatomy and physiology, biology, and statistics. Those are the ones that carry weight. A B- in a nutrition elective is not the same problem as a B- in A&P.

Why retaking a class barely moves your GPA

Let's kill this idea early, because people spend real money on it.

If you've finished a bachelor's, you're carrying 120-plus credit hours. An A in one 4-credit class moves your cumulative GPA by hundredths of a point. As GPA repair, it doesn't work.

So why do it? Because you're sending a message. That C+ in chemistry was four years and one entire career ago. You've since learned to study while working three twelves, and you can prove it by earning an A in the same subject that beat you. Admissions committees read that as growth, and growth is what they're actually screening for.

One caution that changes the math: NursingCAS counts both attempts, even if your university's grade-replacement policy wiped the old grade off your transcript. So the retake doesn't erase anything. It adds a second, better data point.

Should you retake the same class or take a harder one?

This is the part that separates a good retake plan from a wasted semester.

Don't retake the same course. Take the harder one in the same subject. You cover the same foundation, and you show a committee that you went looking for a challenge rather than a do-over.

• Chemistry. Take biochemistry or organic chemistry instead of repeating general chemistry.
• Anatomy and physiology. Take A&P II, or an advanced anatomy course, instead of repeating A&P I.
• Biology. Take microbiology instead of repeating general biology.
• Pharmacology. Take advanced pharmacology if your target programs count it.
• Statistics. Take statistics and research methods. Every program is a doctorate now, which means a research project, and this course gives you something real to say about it.

If you genuinely need the foundation first, retake the basic course. There's nothing wrong with that. But if you're only taking one class in a subject, take the advanced one.

Should you add a graduate-level course?

If your GPA is under 3.4, yes. This is one of the few moves that reliably changes how a committee reads you.

A graduate course answers the question admissions is actually asking, which is not "can you pass chemistry" but "can you handle doctoral-level work." One graduate science course with an A does more for a 3.2 applicant than two more undergraduate retakes.

The pattern that works: clean up one or two undergraduate grades, then add a single graduate-level course on top. You don't need everything at the graduate level. You need one piece of evidence.

This matters even more if you hold an ADN and you're applying to programs that accept one. You can see which programs those are in our guide to becoming a CRNA with an ADN.

What grade do you need on a retake?

Higher than you think, because a mediocre retake is worse than no retake.

• Target: A or A-. This is the goal. It's the grade that tells the story.
• Acceptable: B. Shows real improvement.
• Avoid: anything under a B. Retaking a class and pulling another B- actively confirms the concern you were trying to erase.

If you can't commit enough time to earn at least a B, wait for a semester when you can. A second weak grade in the same subject is a worse signal than one old weak grade.

What should you check before registering?

Three things that save people money and semesters:

• Your hospital may pay for it. Plenty of facilities offer tuition reimbursement for prerequisite coursework, and some large academic medical centers cover several courses outright. Ask HR or your unit educator before you pay out of pocket.
• Ask programs whether your old course still counts. Expiration policies vary and many aren't published. Email admissions and get it in writing. People retake classes they never needed to.
• Plan around labs and deadlines. Science courses with labs run on limited schedules and often only one semester a year. Two or three retakes needs a real timeline, built backward from your application deadline.

Our Final Thoughts

The applicants who get the most out of retaking aren't the ones who retake the most classes. They're the ones who pick two courses deliberately, take the harder version, and earn an A.

Before you register for anything, email your target programs and ask which GPA they calculate and whether your old coursework has expired. It's an afternoon of emails, and it's the difference between a semester that changes your application and a semester that just costs you $1,800.