The present study was designed to evaluate the effect of gastrointestinal nematodes on male fertility and some biochemical parameters in rams and modulating this effect by using albendazole. Twenty rams aged 1.5 - 2 years old weighting 40 – 45 kg belonged to a private farm at Sharkia Province were used in this trail. Rams were divided into four equal groups (5 each). 1^stgroup clinically healthy rams free from parasite (control group), 2^ndgroup clinically healthy rams free from parasite received 5mg albendazole/kgm bwt one dose, 3^rd group rams gastrointestinal nematodes infested non treated and 4^th group gastrointestinal nematodes infested and treated with 5mg albendazole/kgm bwt. one dose. Blood, fecal and semen samples were collected from all rams at 7^th, 14^th and 28^th day post treatment for biochemical analysis evaluate semen character and evaluate efficacy of albandazole against gastrointestinal nematodes. Fecal examination revealed presence of gastrointestinal nematodes eggs as Haemonchus spp, Trichuris spp, Trichostrongylus spp., Ostertagia circumcieta and mixed infection Trichuris + Haemonchus and Ostertagia +Trichostronglus. Reduction of egg count of gastrointestinal nematodes 100 % at 14^th day post albendazole treatment. Healthy rams received albendazole show significant decrease in testosterone hormone, sperm cell concentration, individual motility, alive sperm, total protein, albumin and globulin. Beside significant increase in sperm abnormality and insignificant decrease in ejaculate volume, coupled with insignificant increase in serum and seminal plasma trace elements, ALT, AST, Alp, urea and creatinine. Rams infested with gastrointestinal nematodes show significant decrease in testosterone hormone, sperm cell concentration, individual motility, live sperm, serum and seminal plasma trace element, total protein, albumin and globulin and significant increase in total abnormality, liver enzymes (AST, ALT & ALP) urea and creatinine. Beside insignificant decrease in ejaculate volume was shown. Infested rams treated with albendazole show return the previous parameter to nearly normal levels at 28^th day post treatment. It could be concluded that the albendazole effective against gastrointestinal nematodes and ameliorating its adverse effect in rams fertility and biochemical parameters but its have transit adverse effect in male fertility so; it is not used during mating period.