The aim of this study was to determine the effects of dietary supplementation with red algae powder (Chondrus crispus) on the growth performance, carcass traits, lymphoid organ weights and intestinal pH y in broiler chickens. A total of 300 1-day-old B34 line male broiler chickens were randomly allotted to three treatments, four replicates per treatment and 25 birds per replicate. The experimental treatments consisted of a basal diet (T0) and dietary supplementation of 0.30 (T2) and 0.40% (T2) red algae powder. Body weight at 1, 21 and 32 days did not show significant differences (p>0.05) among treatments. At 21 days, T1decreased (p<0.05) the feed intake and feed conversion ratio. However, from 22 to up to 32 days, these productive indicators increased (p<0.05) with the use of the natural product (red algae powder) tested. Meanwhile, T1 improved (p<0.05) the carcass and breast yields and decreased the abdominal fat yield, and T2increased (p<0.05) the relative weights of the bursa of Fabricius and the thymus. The relative weight of the spleen, the other edible parts and the intestinal pH did not change (p>0.05) with the red algae supplementation. The dietary supplementation of 0.30% red algae improved the growth performance (at 21-day-old) and some edible parts; also, the dietary supplementation of 0.40% increased the relative weight of the lymphoid organs, without changing the intestinal pH of broilers.