Diazinon is an Organophosphate Insecticide (OPI) is commonly used in agriculture to protect of crops and to control pests in home gardens and farms. Many alterations observed by diazinon have been described, such as; alterations in blood factors (RBC, Hb and Hct), plasma testosterone and glucose levels. We selected 12 albino Wistar rats weighting between 220-280 g were divided into two experimental groups, as follow, control group and diazinon treated group. The effects of diazinon, on rat interstitial cell testosterone production, blood factors and plasma glucose levels were evaluated. Male rats were treated orally with a single dose of 1/4 LD₅₀ of diazinon. Animals received treatment for 28 days. Present results indicated that in diazinon treated group, plasma glucose and testosterone levels increased compared to control. Also in diazinon group, reduce of blood factors were observed than control. In conclusion, diazinon disturbs the synthesis of testosterone and glucose release from liver into blood and it led to anemia.