Eight strains of lactic acid bacteria, including Bifidobacterium longum B6 and 15708, Lactobacillus acidophilus N-1 and 4356, Lactobacillus bulgaricus 448 and 449, and Streptococcus thermophilus MC and 573 were investigated for their folate synthesizing ability by applying the high-performance liquid chromatographic method. The results showed that lactic acid bacteria synthesized maximum levels of folate in six hours in fermented milk. B. longum B6 demonstrated the highest folate synthesizing ability, and B. longum 15708 also produced folate satisfactorily. These two strains increased folate 3.5 and 2.4 fold, respectively, after 6h fermentation at 37 ℃. 5-Methyltetrahydrofolate was the main derivative of folate found in fermented milk.