Boric acid and borate are abundant in the nature and widely used in industrial, agricultural and cosmetology applications. However it is informed as toxic in a high dose. Residents of Arica-Chile with boron-rich geology deposits are regularly exposed to higher levels in drinking water in concentrations of 6. 0 and 12.0 mg/L. The objective of this study was to analyze the damage in the masculine reproductive apparatus of mouse CF1, exposed to boric acid in concentrations of 0.54; 2.0-6.0 and 12.0 mg/L, after 60 days of treatment. Male gonad segments were fixed in Bouin's solution for 6 hours and embedded in paraffin, longitudinal sections (5 mm) were processed for histology using the hematoxyline/eosin method. The results observed in treated animals indicate a significant increase in the weight, volume and size of testicles and seminal vesicles. The histological analysis of testicle shows in treated an epithelium notoriously altered with vacuohzations, scarce gonias and few spermatids. Gonias present picnoticals nuclei, suggesting apoptosis. In conclusion boron in high dose produces important cytotoxics effects, with degeneration of epithelium of seminiferous tubules, possibly inhibiting the spermiation, causing testicular hypertrophy, altering the masculine reproductive patterns and a reduction in fertility of mice CF1