Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Biomedical Technology in the Faculty of Health and Wellness Sciences at the Cape Peninsula University Of Technology 2014 / Oxidative stress (OS) plays a central role in the progression of diabetes mellitus (DM). Prevention of DM and its complications is a challenging health problem as it impacts on various organ functions, including reproduction. Diabetes mellitus with hyperglycaemic condition generates high production of reactive oxygen species. An imbalance between antioxidant mechanism and reactive oxygen species generates oxidative stress. OS damages the sperm membrane by oxidation of polyunsaturated fats which in turn reduces the sperm motility and ability to fuse with the oocyte and OS directly damage sperm DNA, compromising the paternal genomic contribution to the embryo development. Recent experimental evidence shows that modulation of oxidative stress and natural antioxidants may determine the outcome of male reproductive function. Previous investigations indicate that the supplementation and treatment with phytomedicine might play role in the prevention and management of DM and its subsequent complications on male reproductive function. This study explored the pharmacological potential of kolaviron (KV) on testicular and epididymal tissue in diabetic and non- diabetic Wistar rats. All experiments were conducted for a period of six weeks. Male Wistar rats (240–290 g) were randomly divided into 5 groups (n=12) where all the rats received a standard diet. Non diabetic rats control group and other four groups injected with different treatments. Non diabetic rat (N) received vehicle: Dimethylsulfoxide. Diabetes rats (D) were induced by a single intraperitoneal injection of freshly prepared streptozotocin (STZ) solution, 50mg/kg body weight. The N and D were treated with kolaviron (100 mg/kg body weight) orally, five times a week .The last group, diabetic rats were given subcutaneously injection of the standard anti-diabetic drug, insulin (0.2 u/kg) every second day. After the feeding period, testicular and epididymal tissues were collected and were analysed. All parameters were determined using appropriate methods in homogenized tissues. Data were expressed as mean ± SD. Plasma glucose as well as malondialdehyde (MDA) was significantly higher, while body, testicular and epididymal weights were lower in the D group compared to the N group and N+KV. Both kolaviron and insulin were able to ameliorate these effects. Testicular and epididymal antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in induced diabetic rats were significantly (p<0.05) low compared to diabetic control group. However, KV treated group shown significantly higher SOD, CAT and GPx activities compared D group. In conclusion, our findings demonstrated that KV could improve antioxidant enzymes and modulate STZ induced diabetic related oxidative stress in the male reproductive system. Kolaviron can potentially be used as an anti-diabetic treatment, however further studies are needed. Key words: Oxidative stress, Diabetes mellitus, antioxidants, kolaviron, epididymal tissue, testicular tissue, superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation, streptozotocin