The present study describes the antifungal potency of Nigella sativa seeds extract and the effect of immunomodulatory of N. sativa against aflatoxin- fed mice. Disc diffusion method was used for antifungal efficacy of aqueous extract of N. sativa. In animal experiments, lymphoid cell count, total and differential counts of PEC, the phagocytic activity of PEC and detection of the plaque-forming were determined. E-rosette-forming cells (RFC), T-cell mitogenesis assay cells, ALT and AST were detected. The aqueous extract of N. sativa (50%) exhibited high inhibition zone with most of isolates of R. stolonifera.The results indicated that treatment of mice by using N. sativa showed marked rise in the number of cells from thymus and PLN with dose 0.50 g and absolute number and comparative ratio of macrophages (P < 0.01) with the doses 0.40 and 0.50 g. There is gradually rise in the scavenger activity of PEC with the dose 0.50 g at 60 min. Serum level of ALT was markedly reduced with dose 0.50 g as compared with a control group. These results indicated that N. sativa is promising modifier of biological response.