This study was performed to explore the effects of aqua-exercise program on back pain, flexibility. time of exercise and self-efficacy in the women with chronic back pain. The design of this study was a equivalent pre-post test experiment. The subjects consisted of 31 women living in seoul. They underwent tests of back pain. flexibility. time of exercise and self-efficacy as baseline data before aqua-exercise program. The aquatic exercise was based on the Back hab and was consists of 60minutes session, 2 times a week for 5 weeks. Data were analyzed with percentage, mean, standard deviation, t-test and pearson correlation coefficient using SAS program. The results were as follows. 1. The back pain has significantly decreased after aqua-exercise program. 2. The dorsal flexibility has significantly increased after aqua-exercise program. 3. The time of exercise has significantly increased after aqua-exercise program. 3. The Self-efficacy has significantly increased after aqua-exercise program. The findings showed the aqua-exercise program could be effective in decreasing the back pain and effective in increasing the flexibility, time of exercise and self-efficacy. It can be suggested the aqua-exercise is effective in the health promotion of the women with chronic back pain.