PCR-RFLP analysis of the rDNA-ITS (internal transcribed spacer) region was applied to 174 yeast strains belonging to 30 species of oenological significance and including 27 type strains in order to define a rapid identification protocol for yeast colonies. DraI-or HaeIII-PCR-RFLP patterns were species-specific with the exception of teleomorphic and anamorphic forms. An improved protocol taking about 30 h was used for the detection and quantification of yeast species occurring in the course of a spontaneous wine fermentation at industrial level. Wine samples were taken and plated daily on an agar medium and the developed colonies were analysed by PCR-RFLP after 24 h of incubation. A representative sample of these colonies was also identified by traditional methods. Both procedures gave identical results. However, PCR-RFLP analysis allowed a more precise enumeration of the yeast populations, proving to be a reliable and simple method for monitoring the development of the yeast community throughout wine fermentation.