This study was conducted to investigate the potential origin of Weissella species, which were found in ingredients of kimchi, such as salted Chinese cabbage, radish, green onion, red pepper powder, pickled shrimps, garlic, and ginger. Ten strains of Weissella species (Weissella thailandensis, W. kimchii, W. koreensis, W. minor, W. halotolerans, W. hellenica, W. kandleri, W. confusa, W. viridescens, and W. paramesenteroides) and lactic acid bacteria isolated from ingredients of kimchi were analyzed by SDS-PAGE of whole-cell proteins. Several strains with patterns identical to those of Weissella kimchii were isolated from green onion. On the basis of biochemical characteristics and 16S rDNA sequence comparisons, these strains were identified as Weissella kimchii, suggesting green onion as a major origin of Weissella kimchii found in kimchi.