1. 1. Ross male broiler chicks growing from 14 to 28 days of age were fed 14 and 20% protein diets (4 kcal day −1/body wt 0.66) or 20 and 28% protein diets (2.8 kcal day −1/body wt 0.66) in a 2 × 2 factorial arrangement to determine the effects of protein and energy intakes on in vitro lipogenesis (IVL) and net glucose production (NGP). Plasma concentrations of insulin, glucagon, thyroid hormones (T 3 and T 4) and somatomedin-C (Sm-C) were estimated by radioimmunoassay. 2. 2. There was a significant ( P < 0.05) decrease in IVL in the chicks given the higher daily protein intake. 3. 3. The higher protein intake increased ( P < 0.05) NGP while the lower energy intake decreased ( P < 0.05) NGP. 4. 4. Insulin, both thyroid hormones and Sm-C were affected by dietary energy and protein intakes.