This study was performed to investigate the effects of dietary supplementation with 2 boron compounds, boric acid and borax, on growth performance and some biochemical parameters in broilers. A total of 216 one day old broiler chickens were randomly assigned to 9 equal groups fed with commercial diets supplemented with 0 (control group) and 10, 50, 100, 250 mg/kg of diet B from either boric acid (BA) or sodium tetraborate decahydrate (borax. BX) for 42 days. Body weights and weight gains, food consumption and food efficiency were weekly recorded and on day 42, serum AST, ALT, GGT, ALP, CK activities and glucose, triglyceride, total cholesterol, HDL and LDL-cholesterol, total protein, albumin, globulin, creatinine, Ca. P and Mg concentrations were determined. Boron supplementation has not significantly affected growth although food efficiency was negatively altered with 250 mg/kg borax. Decreases in AST, ALT and CK activities as well as in Ca, Mg, P (insignificantly), triglyceride and LDL-cholesterol concentrations coupled to an increase in HDL-cholesterol concentrations were observed particularly in borax treated birds whereas glycaemia was markedly depressed in 50, 100 and 250 mg/kg boric acid treated chickens. These results indicate that boron mainly as borax form may act on general metabolisms, electrolyte balance and lipid profiles but further studies are needed to identify with accuracy boron metabolic actions.