The aim of the present study was to investigate the effects of adding Ginseng (Panax ginseng) on intestinal eosinophilic granule cells of the intestine in rainbow trout (Oncorhynchus mykiss). The experimental groups were fed with 0, 100, 150 and 200 g/kg of aqueous ginseng extract diet, respectively. The results showed that ginseng had no significant effect on the mean number of intestinal eosinophilic granule cells per field area in the second (0.1% ginseng extract) and third (0.15% ginseng extract) groups in both proximal and distal segments of the intestine (P>0.05). The mean number of intestinal eosinophilic granule cells in forth group (0.2% ginseng extract), however, significantly increased when compared to the control in both anatomical regions (P<0.05). In all four groups, the mean number of intestinal eosinophilic granule cells per microscopic field was numerically greater in the distal region of the intestinal wall than its proximal segment, but the differences were not statistically significant (P>0.05).