Paecilomyces sinclairii was administered ad libitum feeding at percentage levels of 0, 1.25, 2.5, 5 and 10 percentage (calculated about 8 g/kg)/feeder for a period of 3 months. There was no observed clinical signs or deaths related to treatment in all groups tested. Therefore, the approximate lethal dose of P. sinclairii was considered to be higher than 8 g/kg in rats. Mild decreases in body weight gain were observed dose-dependently in P. sinclairii treated groups in dose response manner after 2 weeks. Interestingly, the weight of abdominal adipose tissues surrounding epididymides were greatly reduced by this Dongchunghacho, in parallel with the mild increase in body weight gain. However, the absolute weight change of other organs was not observed. There were not significantly different from the control group in urinalysis, ocular examination, hematological, serum biochemical value and histopathological examination. From these results, it is concluded that the no-observed-adverse-effect level (NOAEL) of P. sinclairii is less than 1.25% (1 g/kg) in rats in the present study.