The present study investigated the effects of dietary allspice powder supplementation on welfare status of Tilapia, Oreochromis mossambicus assessed by hemato-immunological and serum biochemical parameters. Five diets were formulated to contain 0 (control), 5, 10, 15 or 20g of allspicekg(-1) of fish feed. Fish were fed experimental diets for 60days. Supplementation of allspice powder at 10gkg(-1) positively influenced the serum glucose, plasma lysozyme activity and myeloperoxidase activity. Dietary allspice powder at 15gkg(-1) also positively influenced the serum biochemical parameters (total protein, albumin and globulin) and plasma lysozyme activity. However, 20gkg(-1) allspice powder group had significantly lower values of respiratory burst activity and red blood cell count than other experimental groups (P<0.05). In conclusion, the results of the present study demonstrated that supplementation of allspice powder at 10 or 15gkg(-1) for 60days, had beneficial effects on improvement of some immunological and serum biochemical status of O. mossambicus. These findings suggest that dietary supplementation of allspice powder might further improve the resistance to fish pathogens.