Boron is a chemical element widely used in many industrial activities. Exposure to it affects many organs in mammals, mainly reproductive male organs. This work evaluates boron effect in testis. For this purpose, 12mg Boron/L of drinking water, equivalent to Arica tap water, was given for 42 days to 85 days old CFl male mice (experimental group). Another group (control group) drunk tap water of Santiago (0.6mg Boron/L) was used. Testicular histopathology and morphometric analysis was done. These studies showed that Borum induces alterations such as epithelial vacuolization, blockage of the tubular lumen and atrophy. Morphometrical data showed that Borom induces also enlargement of tubular diameter, epithelial height and tubular lumen. Therefore, it is concluded that Boron acts as testicular toxicant and that further studies are needed to establish its mechanism of action upon spermatogenesis