In summer, most of growth performance traits studied of the New Zealand White (NZW) broiler male rabbits were inversely affected. Final live body weight, body gain weight, daily feed intake, feed cost, return from body gain and final margin, weights of carcass, fore part, intermediate part, hind part, head, kidney and kidney fat, as well as, blood total protein, albumin, globulin, albumin-globulin ratio and total lipids, were lower in summer than in winter. Supplementation of heat-stressed rabbits with palm oil (10 per cent of the diet) improved final live body weight. Drinking cool water showed the highest body weight, total body gain and margin percentage.