This study was conducted to evaluate the effect of different feed formulations, fattening period and sex of broiler chickens on absolute carcass conformation measurements (metatarsus length, keel length, breast depth, breast angle and thigh girth) and conformation indices of medium-growing Master Gris chickens. The results showed that, as induced by intensive fattening, body weights were greater and carcass quality, expressed through conformation measurements, was better than the values characteristic of this hybrid (as the hybrid is designed for extensive farming). Regardless of the time of slaughter (at 49 or 63 days of the fattening trial), male chickens had better carcass conformation values (P<0.05), compared to females, and the 14-day extension of the fattening period led to better values for both absolute and relative carcass conformation measurements in both males and females (P<0.05).