AbstractThe biochemistry and physiology of 2,3‐butanediol metabolism has been studied in a number of selected yeast species. Candida utilis CBS 621 exhibited diauxic growth on 2,3‐butanediol. The first phase was characterized bu the utilization of the two optically active stereoisomers and associated accumulatoin. In the second phase of growth the meso‐form of 2,3‐butanediol was utilized together with acetoin. An attempt is made to explain these phenomena on the basis of the substrate specificity of the two enzymes which oxidize 2,3‐butanediol in C. utilis. Although whole cells oxidized acetoin and diacetyl at high rates, attempts to identify the enzymes responsible for these oxidations were unsuccessful. In C. utilis and other yeasts metabolism of 2,3‐butanediol probably involves a cleavage of the substrate into C2‐units which are assimilated by the glyoxylate cycle. In the few yeasts which have been found to grow on 2,3‐butanediol differences may be encountered with respect to the substrate specificity for the three stereoisomers of 2,3‐butanediol. For example, Candida salmanticensis CBS 5121 showed no diauxis growth and utilized only two of three stereomers.