Microtubules are an essential part of the cytoskeleton and assist in multiple cellular processes like intracellular transport and cell division. Acetylation in microtubules is a prominent post-translational modification in neurons and it is also a well-known marker of stable microtubules. However, it is not known why stable microtubules are more acetylated than dynamic microtubules. There are two models to explain this phenomenon. The first is that stable microtubules are preferably acetylated and the second is that both are acetylated equally, but dynamic microtubules are destabilized by acetylation. Previous research has shown that dynamic microtubules may in fact be preferentially acetylated, supporting the second model. We have found that at physiological salt concentrations, short dynamic microtubules are more acetylated but no correlation was found between length and extent of acetylation in stable microtubules. We are currently studying how acetylation varies in stable and dynamic microtubules by measuring the rate of change of lengths of acetylated microtubules.