1. Some of the physical, chemical and kinetic properties of catfish liver lipogenic enzymes (acetyl-CoA carboxylase and fatty acid synthetase) were investigated. 2. The liver lipogenic enzymes of catfish exhibited maximal activity at 37 degrees C, even though these fish usually live at temperatures not above 24 degrees C. 3. The activity of the lipogenic enzymes of catfish liver was always low, regardless of the proportions of lipids or carbohydrates in the diet and could not be raised by insulin administration. 4. Under the conditions of the experiments, catfish liver fatty acid synthetase produced more stearate than palmitate and no myristate.