Primary systemic Bacillus pyocyaneus infection is infrequent enough to merit discussion. This organism is usually considered as being of low pathogenicity, manifesting its presence occasionally as a secondary invader in localized pyogenic processes. Indeed, it has been found as an apparently nonpathogenic cutaneous parasite, showing some predilection for warm, moist, flexor surfaces. It is found as a secondary invader in such conditions as furuncles, infected wounds and septic pneumonia. It was formerly thought that even in these local infections B. pyocyaneus occurred only as a nonpathogenic parasite. Kossel1 collected a few cases from the literature, all in children in whom a fatal illness was found to be due to an infection of the blood stream with this organism. In another review of the literature, Rolly2 collected a series of cases of infections of internal organs in which Bacillus pyocyaneus was either the sole or an associate invader. In this list