The safety of two species of entomogenous fungi, Cordyceps militaris (FRIES) LINK and Paecilimyces fumoso-roseus (WIZE) BROWN and SMITH was tested on laboratory mice. Acute oral dosages of 4.9×10⁸ spores/mouse for C. militaris and 5.54×10⁸ spores/mouse for P. fumoso-roseus were administered for a one week experimental period. No recoveries of the target oranisms were recorded from any of the animals tested and there were no significant differences in terms of body weight, food and water consumption and blood counts. The safety of these two species of fungi on murine tissue is thereby established.