PURPOSE: While Self Natural Posture Exercise, SNPE, widely practiced in Korea is claimed to be effective, it has not been systematically demonstrated. This study examined whether SNPE is effective in pain, functional movement, and fitness improvement. METHODS: Twenty four women with chronic pain at least last 3 month prior to study participated (27.5±5.8 yrs, 23.0±3.8 kg/m²) and were divided into two groups; SNPE group (EG; n=12) and non-exercise group (NG; n=12). Subjects in EG participated in 12 weeks of exercise program consisted of 60 min per session, twice a week, while those in NG did not. Those in EG were tested before and after the program, and those in NG were tested twice in the same time interval. The pain perception was evaluated by Short-Form Mcgill Pain Questionnaire (MPQ). Movement tests were performed using Functional Movement Screen (FMS). Physical fitness was evaluated by grip and lower back strength, sit-and-reach, and back extension. RESULTS: Pain perception in EG was decreased (pre; 9.5±7.2 vs. post; 3.5±2.8), and group difference was noticed (p<0.01). Deep squat in EG increased (1.3±0.5 vs. 1.9±0.5, p<0.005). Hurdle step in EG increased (1.0±0.0 vs. 1.6±0.4, p<0.005), and group difference was noticed (p<0.05). Inline lunge both in EG (1.4±0.6 vs. 2.6±0.4, p<0.001) and in NG (1.5±0.5 vs. 2.2±0.7, p<0.001) increased. Shoulder mobility in EG increased (1.9±0.7 vs. 2.9±0.2, p<0.001), and group difference was found (p<0.05). Active straight leg raise in NG decreased (2.7±0.4 vs. 2.1±0.7, p<=0.05), but not in EG (2.7±0.4 vs. 3.0±0.0). Push up in EG increased (1.0±0.2 vs. 1.6±0.4, p<0.005). Rotary stability both in EG and NG did not show pre and post trial differences, but group differences were noticed (p<0.05). FMS total score both in EG (11.4±1.5 vs. 15.4±1.7, p<0.001) and in NG (12.1±1.7 vs. 13.2±2.0, p<0.05) increased, and group differences were noticed (p<0.05). Strength parameters were not changed. Sit-and-reach in EG (19.7±6.4 vs. 22.7±6.0, p<0.01) and back extension in EG (53.4±8.4 vs. 58.5±7.8, p<0.05) increased, and group differences in both were noticed (p<0.05). CONCLUSIONS: It is demonstrated that SNPE is valuable exercise modality to release pain perception, to improve functional movement, and to enhance flexibility in women experiencing chronic pain.