Purpose: This study was conducted to develop and test an explanatory model on functional capacity in patients with chronic obstructive pulmonary disease using path analysis. Methods: Data were collected from 149 chronic obstructive pulmonary disease patients using 6-minute walk test, measurement of oxygen saturation, pulmonary function test, and self-reported questionnaires from June to October, 2005. The collected data were analyzed using SPSS/WIN 12.0 program and AMOS/WIN 4.0 program. Results: The overall fitness indices of modified model were good($x^2$ = 14.324, p = .281 GFI = .981, RMSEA = .006, AGFI = .944, NFI = .927, NNFI = .999, CFI = .999, PNFI = .613, $x^2$/df = 1.194). Functional capacity was influenced directly by age(${eta}$ = -.304, p = .000), dyspnea(${eta}$ = -.278, p = .000), self-efficacy(${eta}$ = .240, p = .000), social support(${eta}$ = .175, p = .004), pulmonary function(${eta}$ = .169, p = .008), and oxygen saturation(${eta}$ = .099, p = .048). These variables explained 39.3% in functional capacity. Conclusion: The findings of this study suggest that comprehensive nursing interventions should focus on decreasing dyspnea and increasing self-efficacy, social support, and oxygen saturation. In this perspective, pulmonary rehabilitation would be an effective strategy for improving functional capacity in patients with chronic obstructive pulmonary disease.