Rapid identification and detection of Oenococcus oeni was achieved by species-specific PCR. Two primers flanking a 1025 bp region of the O. oeni gene encoding the malolactic enzyme were designed. The expected DNA amplificate was obtained only when purified DNA from O. oeni was used. The identity of PCR product was confirmed by nested PCR and restriction analysis. Within 8 h, 103 cfu ml−1 of oenococci were detected in fermenting grape must containing 107 yeast cells, whereas the detection limit in wine was 104 cfu ml−1. The rapidity and reliability of the PCR procedure established suggests that the method may be profitably applied in winery laboratories for quality control.