Hairs were detected in the feces of wild lions collected at the Mahale Mountains National Park, Tanzania. The materials were examined for their scale pattern, medulla arrangement, and ultrastructure of longitudinal sections. The observed features coincided with those of the chimpanzee, so that the hairs were judged to be from chimpanzees. The present results suggest that black hairs in lion feces can be identified as belonging to chimpanzees based on observations by scanning electron microscopy.