There are no studies to guide the optimal duration of therapy in severe community-acquired pneumonia (CAP). The aim of this study was to determine whether 7 days of antibiotic treatment is equivalent to longer-course therapy in severe CAP. In this prospective observational study, we included patients with severe CAP (CURB65 score 3-5) admitted to the hospital with signs and symptoms consistent with pneumonia. A propensity score, derived through multiple logistic regression, was used to match patients into two groups: treated for 7 days vs. treated for >7 days. Patients who died, were admitted to the intensive-care unit, developed complicated pneumonia, failed to reach clinical stability or had positive cultures for microorganisms requiring prolonged treatment within the first 7 days were excluded. Patients outside the mutual range of the propensity score were also excluded. The primary outcome of this study was 30-day mortality. Secondary outcomes were subsequent requirement for mechanical ventilation and/or inotropic support and the development of complicated pneumonia or re-admission within 30 days. Four hundred and twelve patients were suitable for derivation of the propensity score. After matching on propensity score, 164 patients treated for 7 days were compared with 164 treated for >7 days; they were well matched in terms of age, gender, comorbidities, and physiological parameters. The results showed no significant differences in the primary and the secondary outcomes between the two groups. This study therefore suggests that, in the majority of severe CAP patients who have clinically responded, antibiotics can be safely discontinued at 7 days.