PURPOSE: This study was done to identify practical exercise performance and to define the factors related to exercise performance in middle-aged women. METHODS: The researchers collected data from 206 middle-aged women, ages 40 to 59. The measurements used were a scale for degree of exercise performance, and self-efficacy scale, affect, perceived barriers and benefits related exercise, body-shape perception, and the youngest child's education stage. The data were analyzed with SPSS/WIN 17.0 and SAS program using t-test, ANOVA, and stepwise multiple regression. RESULTS: Exercise performance showed significant differences according to body-shape perception (F=5.45, p<.01), the youngest child's education stage (F=4.44, p<.05). Exercise performance had a significant strong positive relation with self-efficacy (r=.616), a moderate relation with self-rated health (r=.428) and with affect related exercise (r=.519), a mild relation with perceived benefits (r=.339) and with social support (r=.239), and a negative mild relation with perceived barriers (r=-.330) with 99% significance. Self-efficacy, affect, perceived barriers, and the youngest child's education stage explained 46.4% of a variance in exercise performance in middle-aged women. The factor most influencing was self-efficacy related exercise at 37.9% of the variance. CONCLUSION: We can conclude that self-efficacy, affect, perceived barriers, and the youngest child's education stage should be considered as important factors for developing program of middle-aged women.