['This investigation was set out to determine whether mercury at a very low dose (4ppm) induces testicular damage on murine testis, and if so whether the toxic effects of mercury could be prevented by zinc.', 'One of the following solutions was administered in the drinking water of CD-1 male mice: (1) 4ppm HgCl(2); (2) 800ppm ZnCl(2); (3) 4ppm HgCl(2)+800ppm ZnCl(2); or (4) deionised water; for 12 weeks. At the expiration of the treatment period, animals were sacrificed, testes excised and weighed, and epididymal sperm number taken. The testes were processed for histological examination.', 'Both zinc and mercury significantly (p<0.05) decreased the absolute and relative testicular weights, with mercury producing the highest reduction in weight. Mercury reduced significantly (p<0.05) the epididymal sperm number, while zinc and mercury/zinc produced statistically same effect with control on the sperm number. Histological study showed that mercury at the concentration employed produced remarkable degenerative lesions on the testes, as the zinc-treated group showed a normal morphology. Majority of the animals in the mercury/zinc-treated group exhibited complete or partial protection as evidenced by the morphology of the seminiferous tubules.'] Does low-dose mercury induce testicular damage protected by zinc in mice?