The effect of oxytetracycline at doses of 0.291, 0.461, 0.922, 1.383 and 1.844 g/l in drinking water on the growth rate, lipid metabolism, GOT, GPT, calcium and magnesium was studied on one-day-old chicks and laying hens (Gallus domesticus). Oxytetracycline at a dose of 0.461 g/l increased body weight gain in one-day-old chicks. Oxytetracycline had no effect on hepatic triglyceride and phospholipid levels while cholesterol levels were decreased in one-day-old chicks and increased in laying hens. Oxytetracycline tended to decrease serum cholesterol and to increase serum triglyceride concentrations while its effect on serum phospholipids were inconsistent. Oxytetracycline, although inconsistent, tended to increase GPT and GOT activities in both young chicks and laying hens. Higher doses of oxytetracycline resulted in fatty changes in the hepatocytes and cells of the kidney tubules and lungs in both young chicks and laying hens. With the exception of hepatic phospholipids, all other parameters were higher in laying hens than in young chicks.