The aim of this study was to investigate the influence of dietary fat sources and lysolecithin on growth performance, visceral organ size, and histological intestinal alterations in broiler chickens. Ninety-six 7-d-old male broiler chickens were assigned to 8 treatments in a 2×4 factorial arrangement of treatments with 2 levels of lysolecithin (0 and 145 mg/kg) and 4 different fat sources [poultry fat (PF), yellow grease from Kagoshima (YG1), yellow grease from Kashima (YG2), and yellow grease from Hachinohe (YG3)]. Each treatment had 4 replicates of 3 broiler chickens per cage until 49 d of age. There was no difference in BW gain due to fat sources, lysolecithin, or lysolecithin×fat source interaction throughout the experiment. By feeding lysolecithin, feed efficiency increased (P