Suspensions of four strains of Candida albicans of various concentrations were inoculated in equal amounts into paired vented and unvented vacuum blood-culture bottles. Inocula ranged from 10 to 10(7) organisms. After 48 hours, it was found that unvented bottles contained essentially the same numbers of organisms as the original inocula, whereas heavy growth was observed in vented bottles. When the previously unvented bottles were subsequently exposed to room atmospheric pressure and incubated, all, even those with the smallest inocula, showed heavy growth in two days. It is concluded that Candida yeasts do not multiply under the microaerophilic conditions in such containers, but survive with the capability of subsequent proliferation. To avoid the necessity of employing two bottles, it is suggested that Candida be sought when indicated by venting the container at 48 hours after anaerobic subculture and again examining and subculturing for Candida two days later.