Bacillus species are aerobic, gram-positive, spore forming rods that are widely distributed in soil, dust, stream, and other environmental sources and are regarded as natural organism. But certain species of the genus Bacillus, most notably B.cereus, which is associated with food-borne illness, occasionally have been implicated in the occurrence of fatal illness and complication in a compromised host. We roport a case of pneumonia and bacteremia caused by B.cereus in an 81 year-old man, who had no obvious immunologic compromise. The condition was treated with combination of roxithromycin and gentamicin.