This study was carried out to investigate the effect of supplemental macroalgae (Padina baergensenii) and microalgae (spirulina) as feed additives on body performance, some blood plasma constituents of Frafra male lambs. Twenty Frafra male lambs 5–6-month-old and with initial live body weight 22.85 ± 0.15 kg were divided into four groups for 120 days feeding trial. The lambs were randomly divided into four equal groups (5 lambs each). Control group (T1) was fed the basal diet, second group (T2) fed the basal diet supplemented with 0.2% microalgae (T2), fed the basal diet supplemented with 2% macroalgae (T3), while (T4) fed on the basal diet supplemented with 0.1% microalgae + 1% macroalgae dry / head/ day. Lambs were weighed to determine performance of growing lambs and adjusted their feeding requirements. Blood samples were collected before morning feeding. Final body weight, total gain and daily gain increased for T2 in comparison with T1, but this was slightly increased not significant. Feed conversion improved slightly for T2 compared with T1 and other treated groups (T3 and T4). Plasma total protein, globulin, ALT and glucose increased significantly (P<0.05) for T2 compared with other groups. Cholesterol decreased significantly for T4 compared with other groups, whereas there is no significant difference among groups for urea and AST concentration. As well as total revenue of body weight gain and net revenue as well as economic efficiency were significantly higher for lambs fed Spirulina algae rations than those of control ration.