The aim of this study was to investigate the hitherto unknown potential of Pyrroloquinoline Quinone (PQQ) in regulating diabetes associated testicular dysfunctions and oxidative damages in testis of adult mice. Seven groups such as normoglycemic and PQQ treated controls; STZ-treated and STZ + PQQ treated (5, 10 and 20 mg/ kg/day, separately) and STZ + Vit.C (50 mg/kg) were established. After 18 days of experimentation, alterations in the markers of oxidative stress, various antioxidants, lipid profile, serum insulin, testosterone and testicular histology were evaluated. Administration of single dose of STZ (150 mg/kg b.wt) enhanced not only testicular lipid peroxidation and lipid hydroperoxides levels; but also serum concentration of glucose, cholesterol, triglyceride, low density lipid and very low density lipid; with a parallel decrease in serum insulin, testosterone, and different antioxidants in diabetic mice. However, on simultaneous administration of PQQ, particularly at a dose of 20 mg/kg, most of these adverse effects were ameliorated. While the PQQ (20 mg/kg) decreased the serum glucose by 50%, it increased insulin and testosterone levels by 59% and 169% respectively in STZinduced animals, these results suggest that PQQ may have potential to ameliorates diabetes-induced testicular dysfunction.