To investigate the effect of dried Bacillus subtilis culture on growth, body composition and hepatic lipogenic enzyme activity, female broiler chicks were fed on either no additive (control) or dried B. subtills-culture-supplemented commercial diets (215 g crude protein/kg, 12.85 MJ metabolizable energy/kg) at 10 or 20 g/kg diet for 28 d from 14 to 42 d of age. Body weight, and moisture, fat, protein and ash contents of the body were not influenced by the B. subtilis culture. Feed efficiency. N utilization, the ratio of abdominal fat or liver to body weight, acetyl-coenzyme A carboxylase (EC 6·4·1·2) activity, liver and serum cholesterol contents were significantly lower in treatment groups, while fatty acid synthetase activity and serum cholesterol concentration were not significantly different, compared with the control group. Liver triacylglycerol concentration was decreased in chicks given 20 g culture·kg diet, while serum and carcass triacylglycerol concentrations were significantly lower in treatment groups than in the control group. Serum phospholipid concentration was increased but carcass phospholipid concentration was decreased in chicks given 20 g B. subtilis/kg diet, while liver phospholipid concentration was not significantly influenced. The advantages of inclusion of B. subtilis to the broiler diet included improved feed efficiency, less abdominal fat, reduced triacylglycerol concentrations in the liver, serum and carcass and reduced cholesterol concentrations in the liver and carcass.