AIM:To investigate the effect of a fermented milk containing Bifidobacterium lactis DN-173010 and yogurt strains (BIO ® ) on adult women with constipation in Beijing. METHODS: A total of 135 adult females with constipation were randomly allocated to consume for 2 wk either 100 g of the test fermented milk or 100 g of an acidified milk containing non-living bacteria (control). Stool frequency, defecation condition scores, stool consistency and food intake were recorded at baseline and after 1 and 2 wk in an intention-totreat population of 126 subjects. In parallel, safety evaluation parameters were performed. RESULTS: At baseline, no differences were found between groups. Following consumption of test product, stool frequency was significantly increased after 1 wk (3.5 ± 1.5 vs 2.4 ± 0.6, P < 0.01) and 2 wk (4.1 ± 1.7 vs 2.4 ± 0.6, P < 0.01), vs baseline. Similarly, after 1 and 2 wk, of test product consumption, defecation condition (1.1 ± 0.9 vs 1.9 ± 1.2, P < 0.01 and 0.8 ± 1.0 vs 1.9 ± 1.2, P < 0.01, respectively) and stool consistency (1.0 ± 0.8 vs 1.5 ± 1.1, P < 0.01 and 0.6 ± 0.8 vs 1.5 ± 1.1, P < 0.01, respectively) were significantly improved.Compared with the control group, stool frequency was also significantly increased (3.5 ± 1.5 vs 2.5 ± 0.9, P < 0.01 and 4.1 ± 1.7 vs 2.6 ± 1.0, P < 0.01, respectively), and defecation condition (1.1 ± 0.9 vs 1.6 ± 1.1, P < 0.01 and 0.8 ± 1.0 vs 1.6 ± 1.1, P < 0.01, respectively) and stool consistency (1.0 ± 0.8 vs 1.4 ± 1.0, P < 0.05 and 0.6 ± 0.8 vs 1.3 ± 1.0, P < 0.01, respectively) significantly decreased after 1 and 2 wk of product consumption. During the same period, food intake did not change between the two groups, and safety parameters of the subjects were within normal ranges. CONCLUSION: This study suggests a beneficial effect of a fermented milk containing B. lactis DN-173010 on stool frequency, defecation condition and stool consistency in adult women with constipation constipated women after 1 and 2 wk of consumption.