The present work was conducted to detect the efficacy of garlic extract on Cryptosporidium parvum in experimentally infected mice. Thir­ty six Swiss mice aging 2 — 3 weeks were divided into 3 groups, each of 12 mice. Group I was the infected treated, group II was the infected non-treated control and group Ill was the non-infected non-treated control one. The mice in the infected groups were given 10⁶ C. parvum oocysts. Garlic extract was given orally to mice of the treated group at a dose of I ml / 100 g body weight. Faecal smears from mice of each group were examined every 2 days after staining by modified Zieht Neelsen staining technique and the oocysts were counted in 100 randomly selected field at X 1000 magnification. The results showed that, there was a significant difference in the mean values of oocysts shedding between the infected treated group I and the infected non-treated control group II from the 7^th day post­treatment (d.p.t.) (mean ± SD; 25.17 ± 5.56 and 40.33 t 16.72 respec­tively) until the termination of the experiment on the 25^th d.p.t. (mean ± SD) 0.94 ± 1.43 and 55.75 ± 19.79 respectively). The therapeutic effi­cacy of garlic extract on cryptosporidiosis in experimentally infected mice was 58.3%. At the termination of the experiment on the 25^th d.p.t., the mice of the three groups were sacrificed and the ilea were col­lected for histopathological examination. The villi of Ilea in the infected-treated mice in group I showed no pathological changes and regained their normal appearance. They showed neither atrophy nor desquamation of villi when compared to ilea of infected-non treated control mice. At the end of experiment, some infected-treated mice (5/12) belonging to group I showed some degrees of oocysts count in faeces, but didn't show neither atrophy nor desquamation of