The present study conducted to evaluate the effects of soybean lecithin on growth indices, body composition, digestive enzymes activities and intestinal histomorphometry of Caspian salmon. Ninety fish (350g ± 10) were randomly divided into three treatments with three respective replicates. The first treatment (control group) was fed with commercial feed, while the second group received diet supplemented with 12% soybean oil, and the third one received feed supplemented with 6% soybean oil and 6% soybean lecithin for 90 days. Weight gain was indicative of the statistical superiority of treatment 3 over control group and treatment 2. In addition, FCR of treatment 3 was only significantly different from control group (p≤0.05). There were significant differences regarding moisture content of treatments 2 and 3 in compare to control group (p≤0.05), however, protein and lipid contents of treatments were not significantly different (p≤0.05). Furthermore, energy contents of treatments 2 and 3 were significantly different (p≤0.05). Digestive enzymes activities (protease, lipase and amylase) of treatment 3 significantly differed from treatment 2 and control group (p≤0.05). Morphometric characteristics of intestine including epithelium thickness and external muscle thickness of treatments 2 and 3 were significantly different from those of control group (p≥0.05). In conclusion, supplementing Caspian salmon diet with 6% soybean lecithin improved growth and some physiological parameters of the fish.