Abstract: Ninety Starbro broilers of one month age having an initial live weight 1150-1320 g for 15 days (finisher period) were randomly assigned to six treatment which were fed on different levels of soybean oil. In the finisher period (30th to 45th day), total live weight gain of the broilers fed 4% (920 g) and 6% (961 g) soybean oil diet were significantly higher than the broilers fed 0 (764 g), 2 (870 g), 8 (867 g) and 10% (782 g) soybean oil diets. Total feed intake was gradually decreased with increasing levels of soybean oil in the diets. Feed conversion efficiency (FCE) was gradually improved with increasing levels up to 6% of soybean oil and then decreased with above the levels (e.g. 8 and 10%) of soybean oil in the diets. Similarly, the cost benefit ratio (CBR) of T2 (2.15) and T3 (2.17) groups were significantly more satisfactory than the other treatment groups (T0 = 1.92, T1 = 2.09, T4 = 1.97 and T5 = 1.72). So, up to 6% soybean oil may be added in the broiler finisher diet during hot weather in Bangladesh.