Caput and cauda epididymides were biochemically examined for effects of deficiency of zinc. Mature Swiss albino mice were treated with zinc-deficient diet (2-3 ppm zinc) in zinc-deficient, i.e. experimental group and zinc-control diet (100 ppm zinc) in control and pairfed groups, The experimental and control animals fed ad libitum while the pairfeds were provided the same quantity of diet as consumed by the experimental animals. The experiments were run for 2 and 6 weeks at the end of which the animals of the three groups were sacrificed and epididymides were collected for various biochemical estimations and enzyme assays. No significant differences were observed in the epididymal weights of the zinc-deficient (ZD) animals with respect to the control (ZC) and the pairfed (PF) animals. While protein and cholesterol levels increased significantly, deoxyribose nucleic acid (DNA) and zinc (Zn) levels decreased in the ZD animals with respect to the ZC animals. The enzyme assays recorded a significant decrease in the various enzyme activities viz. 5'nucleotidase, beta-galactosidase, sorbitol dehydrogenase and glucose-6-phosphate dehydrogenase in the ZD animals in comparison to the ZC animals. These results reveal a reduction in spermatozoa population, impairment of synthetic and secretory activities of epididymal cells due to disturbed metabolism, improper maturation of spermatozoa, decrease in their fertilizing capacity as well as motility, increase in spermiophagy in cauda epididymis and onset of cellular degeneration in both caput and cauda epididymides. A decrease in androgen levels due to zinc deficiency may have been responsible for many of the above adverse effects. Caput epididymis appears to be more susceptible to adverse effects of zinc deficiency, as its zinc level declined significantly while cauda epididymis is more resistant, It maintained its zinc level and was thus comparatively less affected, The pairfeds too showed significantly altered protein and cholesterol values as well as significant decrease in DNA content and enzyme activities. They had decreased zinc level too. These seem to be stress mediated effects as prolonged restricted feeding may have caused stress in the animals.