This study was carried out to evaluate the effect of magnesium supplementation forms and levels to the diet of broiler chicks on performance and some carcass traits. One day old of 180 broiler chicks (Arbor Acres plus) were allocated randomly into 6 treatment groups of 30 chicks each (2 sources x 3 doses factorial experiment). The distribution of birds was random. Each form of magnesium was added to the basal diet at doses 0, 60 and 120 mg Mg/kg diet.  The study lasted for 35 days. Results showed that, birds fed the control diet that was supplemented with inorganic magnesium recorded an enhancement (P<0.05) in body weight gain, feed intake and feed /gain ratio (feed conversion). Adding the highest supplementation level of Mg (120 mg Mg/ kg diet) to broiler diet recorded significant improvement (P≤0.01) in body weight gain, feed intake and feed conversion. No significant differences were observed in weights of live body, carcass, giblets and   proportions of dressing and giblets due dietary treatments.