The effect of 200, 400 and 600 mg dietary copper sulphate/kg was studied in 64 Japanese quail (Coturnix coturnix japonica) in 1987. The results indicated that addition of 200 or 400 mg/kg to conventional diets of quail 7–42 days old significantly increased (P < 0·05) body weight gain and significantly decreased (P < 0·05) feed intake. There were significant (P < 0·05) increases in carcass, breast and leg weights in some cases; the first two characters had the highest values in the quail fed the diet containing 200 mg Cu/kg. The addition of 600 mg Cu/kg to the diet had an adverse effect on liver weight compared with the addition of 200 and 400 mg/kg. Copper concentration in the liver was not influenced by any rate of copper supplementation.