A total of 560 day-old commercial broiler chicks were used in two experiments conducted to investigate the biotin requirement of broilers fed sunflower seed meal (SSM) based diets. Two basal biotin-deficient diets based on dehulled (Experiment 1) and non-dehulled (Experiment 2) SSM were each supplemented with graded levels of biotin so that the rations had 40, 80, 120, 160, 200, 240 and 280 mcg/kg feed. Therefore a total of 14 treatments were tested. Each treatment was given to duplicate floor pens with 20 chicks each for a period of 28 days. Estimation of the live weights, live weight gain, feed intake, blood glucose and free fatty acid concentrations, lipid contents and weights of liver and kidney, and liver pyruvate carboxylase activity and the records of incidence of dermal lesions, fatty liver and kidney syndrome (FLKS) mortality and leg deformities indicated that in the case of dehulled SSM, dietary biotin of of 160 mcg/kg feed was marginal while at least 200 mcg/kg appeared to be needed for optimum performance of the birds. When non-dehulled SSM was incorporated in the diet, 200 mcg biotin/kg feed was found to be the lowest dietary level needed. However, as it seems that better results could be obtained with higher levels, 240 mcg biotin/kg with non-dehulled SSM is being recommended.