Information on the effect of garlic on the liver and optimal dose of garlic to avoid liver damage is not known. This study was planned to determine the safe dose of garlic. Male wistar rats (110-170g) were fed fresh garlic homogenate (FSH) orally in three different doses (1.0, 2.5 and 5.0 g/kg body weight/day) daily for 28 days. Liver histology, serum transaminases, bilirubin and alkaline phosphatase were estimated at 0, 14, 21 and 28 days in control and experimental animals. 1.0, 2.5 and 5.0 g/kg body weight/day of garlic showed significant (P<0.001) deterioration in liver function tests (LFT's) after 21, 14 and 7 days respectively. A 1.0 g/kg body weight/day dose of garlic was associated with marked histological damage in liver after 21 days. Therefore, three lower doses of garlic (0.1, 0.25 and 0.5 g/kg body weight/day) were given orally to another group of similar rats to determine the safe dose of garlic. LFT's were serially measured and animals were sacrificed on the 29th day of experiment. All three lower doses showed significant deterioration in the LFT's values of animals after 28 days of feeding the freshly prepared garlic homogenate. Both doses of garlic i.e. 0.1 and 0.25 g/kg body weight/day were associated with normal histology of liver, but 0.5 g/kg body weight/day dose of garlic showed morphological changes in the liver of one animal. Therefore, the present study suggests that garlic with high dose has the potential ability to induce liver damage and low doses (0.1 or 0.25 g / kg body weight/day) are safe doses of garlic.