In poultry, the liver is the main organ for the synthesis of triglycerides (TG) and their secretion into the plasma. Secretion of TGs from the liver and their storage in adipose tissue of the abdominal cavity reduces the meat yield. There are controversial reports about the effects of garlic on the levels of TG in the serum and liver of poultry. In this study, different diets that contained various levels of garlic powder were assessed with regards to their effects on the levels of TG in serum and the liver, and on the abdominal fat pad. For this purpose,144 3male Ross broilers who were three weeks old were assigned into four groups of 36 birds each, and fed on diets that were supplemented with 1, 2 or 4% of garlic powder, or with a diet that was not supplemented with garlic (the control group). At the end of the fifth and seventh weeks of the study, 15 chicks of each group were bled and then sacrificed. The livers and abdominal fat pad were removed. Liver and serum TG were extracted and measured by spectrophotometry. The TG levels of serum and the abdominal fat pad were not affected by diet by the end of the fifth week, but diets that contained 2% and 4% garlic powder had a significantly decreased hepatic TG level in comparison with the control group (p<0.05). At the end of the seventh week, a significant decrease in serum and hepatic TG levels was found in the birds that were fed a diet that contained 2% and 4% garlic powder, respectively (p<0.05). Also, the diet with 4% garlic powder significantly decreased the weight of the abdominal fat pad in comparison with the control group (p<0.05). It is concluded that garlic powder has the potential to decrease the levels of TG in the serum and liver in broilers in a dose–dependent manner.