This investigation was designed to appraise the antibilharzial efficacy of garlic. Adult male Swiss albino mice were allocated into two main groups; the first group was non-infected and killed after 6 weeks, while the second one was infected with S. mansoni cercariae and divided into two equal halves to be sacrificed at 6 and 12 weeks post-infection. Both, the non-infected and infected groups were divided into three subgroups: I. non-treated, II. treated with 50 mg/kg of garlic extract and III. treated with 100 mg/kg of garlic extract. Some parasitological parameters (including worm burden, tissue egg load and hepatic granulomas count and diameter) were measured. In addition, hepatic histological examinations were performed. In non-infected mice treated with garlic (50 mg/kg), the histological changes in the inspected organ were generally mild. Concurrently, the high dose of garlic (100 mg/kg) induced hepatocytic hypereosinophilia, vacuolation and necrosis, in addition to nuclear alterations. In infected non-treated mice, hepatic tissue manifested apparent features, including: vascular dilatation, bile ductule proliferation, periportal inflammation, granulomatous reactions and fibrosis, as well as Kupffer cell hypertrophy and pigmentation. Besides, liver cells suffered from cloudy swelling, vacuolation and necrosis. Treating infected mice with the low dose of garlic resulted in significant parasite eradication, considerable reduction in the number of ova/g tissue. In addition, a conspicuous suppression in granulomatous formation and diminutive histopathological changes were observed. Conversely, no major differences were detected in the parasitological or histological observations following the administration of 100 mg/kg of garlic after infection as compared to the non-treated infected groups. Therefore, we can conclude that garlic in low doses has a curative effect on S. mansoni infection and plays a role in ameliorating its pathological consequences, although at high doses the reversal of these effects is observed.