The pathways of glucose catabolism were examined in haploid and diploid strains of the smut fungus Ustilago violacea. Radiorespirometric studies indicated that both of the haploid mating types and diploid strains of the basidiomycete catabolized glucose through the Embden-Meyerhof and hexose monophosphate shunt pathways. The Entner-Doudoroff pathway was not utilized by any of the strains examined. Radiorespirometric data also suggested functioning of an active tricarboxylic acid cycle. In vitro enzyme assays established the presence in this organism of all the enzymes integral to the operative pathways plus the presence of the enzymes of the glyoxylate cycle. Enzyme activities specific to the Entner-Doudoroff pathway were not detected. No major differences in the routes of glucose dissimilation were found between the two haploid mating types or between haploid and diploid forms of this organism.