BACKGROUND: Symptoms of fatigue and dyspnea, treatment with oral corticosteroids, high circulating levels of cytokines, and oxidant/antioxidant imbalance in patients hospitalized with community-acquired pneumonia (CAP) could affect the patients' exercise tolerance and peripheral muscle strength (PMS). OBJECTIVE: To evaluate the functional capacity (FC) of patients hospitalized for CAP and to correlate the FC with length of hospital stay. METHOD: We prospectively evaluated 45 patients (49±16 years; CAP group) and 20 healthy subjects (53±17 years; control group). They were randomized to perform, on separate days, a 6-minute walk test (6MWT), a test of PMS, and the Glittre test (GT). Additionally, the SF-36 questionnaire and the MRC scale were completed and evaluated. RESULTS: There were significant differences between the groups (CAP and controls) for the 6MWT (381.3±108 vs. 587.1±86.8 m) and GT (272.8±104.3 vs. 174±39 sec). The CAP group also presented worse health-related quality of life (HRQoL) scores, reduced strength (quadriceps and biceps), and higher scores of dyspnea. The time required to perform the GT correlated with the length of hospital stay (r=0.35, P=0.02) and dyspnea (r=0.36, P=0.02). Significant correlations were observed between GT and 6MWT (r=-0.66, P=0.0001) and between GT with the physical functioning domain of SF-36 (r=-0.51, P=0.0001). CONCLUSIONS: Patients hospitalized for CAP presented with reduced FC, PMS, and HRQoL during hospitalization. In addition, GT performance was related to the length of hospital stay.