Objective: To observe the curative effect of hydro-acupuncture for treatment of hypomenorrhea. Methods: A total of 72 cases of hypomenorrhea were randomly allocated into an observation group and a control group, with 36 cases in each group. Hydro-acupuncture was used in the observation group and acupuncture treatment in the control group. Menstrual blood volume (MBV) was observed in each phase of treatment in the two groups and the curative effects in the two groups were analyzed and compared. Results: After 3 months of treatment, the total effective rate in the observation group was 100.0% and 91.7% in the control group. The difference between the two groups was statistically significant (P<0.05). In the course of treatment, 1 month and 2 months after treatment, the observation group results were superior to those in the control group (P<0.01; P<0.05) in the improvement of MBV. Conclusion: Both hydro-acupuncture and acupuncture are effective methods for treatment of hypomenorrheal, and hydro-acupuncture is not only faster in its effect but superior to acupuncture treatment in overall efficacy. © 2011 Shanghai Research Institute of Acupuncture and Meridian and Springer-Verlag Berlin Heidelberg.