A medium that initially produced filaments from almost all of its Candida albicans blastospore inoculum contained 1% mycological peptone and 0.2% glucose, final pH 7.4–7.5. The medium was inoculated to 106 cells/ml and incubated at 40 °C. Reversion to secondary blastospores began at a mean of 2.4 h after inoculation. The patterns of utilization of growth nutrients during optimal mycelial growth showed no correlation with the events of filamentation.