AbstractThe molecular structure of aldehydes is closely related to their antimicrotubular effect. Morphological modifications of the microtubular system in living cells after incubation with certain aldehydes are consistent with biochemical alterations detected in previous research. The microtubular arrangement was visualized by an immunofluorescence technique with antitubulin antibodies, while the content of tubulin in the cells was evaluated by a colchicine binding assay. 2‐Nonenal behaved similarly to 4‐hydroxynonenal, a lipid peroxidation product, disorganizing microtubular network in 3T3 fibroblasts and decreasing the amounts of tubulin able to bind labelled colchicine. Nonanal did not significantly impair the tubulin characteristics in the cells, despite the fact that it has been shown to be active on the purified microtubular system; benzaldehyde was ineffective. This would appear to explain the mechanisms of interaction of aliphatic aldehydes which might be suitable for use as antimicrotubular dr