Purpose: The purpose of this study was to examine the effects of aquatic exercise on pain, fatigue, physical fitness, disability in ADL, and psychological variables in women with arthritis. Methods: With a quasi-experimental design, 46 women who has arthritis were assigned into an experimental group (n=23), or a control group (n=23). Data were analyzed with SPSS/WIN using descriptive statistics, t-test and ANCOVA. Results: The mean age of the subjects was 60.9 years in the experimental group and 59.8 years in the control group. The pretest scores of the outcome variables were similar between the two groups except fatigue and waist flexibility. After controlling fatigue and waist flexibility, the experimental group showed more improvement than the control group in Rt shoulder flexibility score (F=4.36, p=.04), sit-up score (F=32.34, p=.00), and muscle strength score (F=30.78, p=.00). The score of disability in ADL decreased in the experimental group (F=5.49, p=.02). The depression score decreased in the experimental group (F=12.01, p=.00), and self-efficacy was improved more than the other variables(F=8.88, p=.00). Conclusion: Aquatic exercise is likely to be an effective nursing intervention to improve physical fitness, to reduce pain, fatigue, and disability in ADL, and to enhance psychological functions in women with arthritis.