Low spermatozoal ATP concentration in the presence of high alpha-glucosidase activity may indicate efficient epididymal function. It was suggested that detached ciliary tufts (DCTs) originated from the epididymis. We compared the spermatozoal ATP concentration and alpha-glucosidase activity in semen of patients with DCTs to that of a control group. Higher ATP concentration and lower alpha-glucosidase activity were found in patients with DCTs in their semen compared to the control group. These results might probably point out impaired epididymal function and further support the proposed epididymal origin of these tufts.