This study was performed to investigate the anthelmentic (nematodes) effect of garlic in Swiss albino mice naturally infected with Aspiculuris tetraptera. Natural infection was determined by the use of cellophane tape method on the perianal region and by the technique of centrifugal flotation of stool samples. The infected mice were divided into three groups; namely, Group 1: garlic treatment groups (n: 18), Group 2: positive control (treated with ivermectin, n: 19) and Group 3: untreated control group (n: 19). The mice in Group 1 were given orally freshly crushed garlic homogenates every day for 7 days. The animals in Group 2 were treated with ivermectin intramuscular at a dose of 0.2 mg/kg body weight. The mice in Group 3 received only serum physiologic orally. After 8 days of administrations, all mice were killed humanely using inhalation anaesthesia and then the parasites in the intestine were counted. It was observed that garlic and ivermectin were 91.24 % and 78.03 % effective against A. tetraptera in naturally infected mice, respectively. Results obtained from this study were compared statistically and differences were found to be significant (p<0.001). It was found that garlic was efficient along the duration of the treatment in mice. Garlic may be useful as an alternative treatment against nematode parasites in animals and human. This article includes a new research using Allium sativum anthelmentic effect on mouse and has been patented.