Putrescine, spermidine, spermine and histamine were analyzed in spermatozoa taken from distinct regions of the bovine epididymis. In addition, the activity of ornithine decarboxylase (EC 4.1.1.17] and diamino oxidase (EC 1.4.3.6), 2 enzymes associated with polyamine metabolism, was studied. During passage of spermatozoa from the caput to the cauda epididymidis, the content of putrescine, spermidine, spermine and histamine decreased markedly. Diamino oxidase activity was detected in extracts of spermatozoa from all segments, but the activity recorded was too low to enable quantitative comparison between the segments. Ornithine decarboxylase could not be detected in the spermatozoa. These variations in polyamine content may influence the membranes of epididymal spermatozoa during their maturation, resulting in alterations of function.