Abstract: High plasma level of cholesterol or triglycerides was associated with poor semen quality and direct adverse effects on testicular function that may lead to male infertility. The effect of fixed oil of Nigella sativa (N. sativa) on male fertility in normal and hyperlipidemic rats was studied. Induction of hyperlipidemia was done by feeding rats on a diet containing 1% cholesterol, 2% sheep fat and 0.5% cholic acid for 2 months. Oil of N. sativa was orally given (0.5mL/rat) for 2 months daily to normal and hyperlipidemic rats. Plasma lipid profile including cholesterol, triglycerides, Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL) was evaluated. Fertility index as determined by sex organ weights, plasma testosterone level and sperms evaluation (sperm motility, sperm abnormalities and sperm count) was investigated. In hyperlipidemic rats (control +ve), there was a marked increase in plasma cholesterol, triglycerides and LDL levels. On the other hand, there was a significant decrease in HDL and fertility index associated with increase in sperm abnormalities. Oral administration of oil of N. sativa to either normal or hyperlipidemic rats improved the fertility index as manifested by increase in seminal vesicle weight, testosterone level, sperm motility and sperm count and a decrease in sperm abnormalities. In conclusion, administration of N. sativa oil to hyperlipidemic rats improved their reproductive efficiency and produced additional protection against hyperlipidemia induced reduction in fertility.