SUMMARYNutritional studies withPycnoporus cinnabarinuswere performed utilizing 26 different media containing various carbohydrate sources. Growth was measured by dry weight. A statistically significant increase in growth was demonstrated for six media. The best growth was obtained in starch-yeast-extract medium. Mycelia from selected media were analyzed for protein composition by polyacrylamide-gel electrophoresis. Analysis of total mycelial protein patterns demonstrated differences depending on the medium being utilized by the organism.