Liquid medium assays for yeasts carbon assimilation tests are the more precise but longer methods. For rapid and automated yeasts identification purposes we analysed the assimilation of 34 carbon compounds by 149 reference strains. Assays were carried in liquid shaken medium (Autobac system) and readings were nephelemetric. Valuable results are obtained in 72 hours and their analysis allowed us to classify substrates for their ability to minimize the number of doubtful results.