The aim of this study was to evaluate the antioxidative/oxidative status of spermatozoa and prostatic fluid in dogs with benign prostatic hyperplasia (BPH) by the determination of total antioxidant capacity and protein peroxidation markers. Study was conducted on 40 intact dogs of various breeds. The dogs were assigned to two groups: BPH group (n=20) and non-affected group (n=20). The second and third fractions of the ejaculate were collected separately by digital manipulation. Total antioxidant capacity (TAC) and the concentrations of SH-groups in sperm and prostatic fluid were determined spectrophotometrically, the concentrations of bityrosine and formylkynurenine were determined using spectrofluorimetric methods. The mean values of TAC in spermatozoa and prostatic fluid were significantly lower (p<0.05), whereas the mean contents of biotyrosine and formylkinurenine were significantly higher (p<0.05) in BPH dogs compared to control dogs. There was no statistically significant difference in the content of SH group between dogs with BPH and control dogs (p>0.05). In conclusion, the results indicate that BPH in dogs is associated with reduced total antioxidant capacity and increased protein oxidation in the prostatic fluid and spermatozoa, and suggest the importance of oxidative stress in the pathogenesis of this condition. The potential role of antioxidants in the prevention and therapy of canine BPH requires further studies.