In this study, effects of bee pollen on some immunological parameters of rainbow trout (O. mykiss) were investigated. In the research, total 120 rainbow trout that averagely weighted 100±10 g were used. Diets containing 1%, 2% and 4% pollen were given to the fish for 21 days. At the end of the experiment, hematocrit value, oxidative radical production (nitrobluetetrazolium-NBT activity), total protein, and total immunoglobulin levels were analyzed in blood samples taken from fish. There was a statistically significant increase in haematocrit level, oxidative radical production, total protein, and immunoglobulin levels of pollen-treated groups when compared to the control group.