The incidence of diabetes mellitus is rapidly increasing in the world. One of the complications of diabetes includes disturbance of the reproductive tract, such as infertility, erectile dysfunction, and endocrine disruption. Nitric oxide (NO) is a free radical produced by most cells including the human male and female reproductive tracts. NO has a dual role where low concentrations are essential for homeostatic cellular biology and physiology, but high levels have detrimental effects relating to cellular damage from this reactive oxygen species (ROS). 8-hydroxydeoxyguanosine (8-OHdG) is an oxidized nucleoside of DNA that is currently used as a biomarker of cellular oxidative stress, where urinary levels can correlate with diabetic nephropathy and retinopathy. Our aim was to investigate the relationship between nitrate/nitrite levels and 8-OHdG levels in the semen of diabetic and non-diabetic men. Concentrations of nitrate/nitrite and 8-OHdG were examined in seminal plasma of 32 diabetic and 35 non-diabetic men. The level of nitrate/nitrite was assayed by colorimetric reaction and 8-OHdG was measured by ELISA. Our results showed that the seminal plasma nitrate/nitrite levels were significantly higher in the diabetic group (p < 0. 01). There were also significantly higher 8-OHdG levels in diabetic men compared to non-diabetic men (p < 0.05). Regression analysis indicated that in diabetic men, nitrate/nitrite levels correlated well with 8-OHdG levels (r = 0.64, p < 0.001). A significant trend between nitrate/nitrite and sperm parameters was not observed. Our data suggests that high levels of nitrate/nitrite in the semen of diabetic men is suggestive of reactive oxygen species induced DNA damage that is correlated with 8-OHdG levels but not sperm parameters. These results support the further investigation of NO and 8-OHdG as biomarkers for assessing male infertility.