OBJECTIVE Patients with community-acquired pneumonia can be allocated into low and high-risk mortality groups by simple clinical criteria. We studied the value of the stratification for outcome as proposed by Fine, et al. to guide the decision for in-hospital versus outpatient treatment in the emergency department. METHODS We studied demographic data, risk group stratification and decision-making for in-hospital versus outpatient treatment in 101 consecutive medical emergency department patients with community-acquired pneumonia. We also analysed predictive factors for hospitalisation of low-risk patients. We obtained complete 30 day follow-up information. RESULTS Forty-three of 44 high-risk patients were hospitalised after medical emergency department triage. Twenty-seven (47%) of 57 low-risk patients were hospitalised as well. Based on routine clinical assessment, hospitalisation of low-risk patients was required for poor medical condition or severe pneumonia (67%), for lack of social support (15%) and for relevant comorbidity (18%). In an univariate analysis, age (p = 0.003), C-reactive protein (p = 0.0006), presence of comorbidity (p = 0.0001), Charlson index (p = 0.0001) and active oral steroid treatment (p = 0.028) were significantly correlated with hospitalisation of low-risk patients. The 30-day mortality rate was 32% in patients allocated to the high-risk group at the time of diagnosis in the emergency department, compared to 0% in low-risk patients. CONCLUSIONS Simple clinical criteria distinguish well between low and high 30-day-mortality risk in patients diagnosed with community-acquired pneumonia. Nevertheless, 47% of low-risk patients require in-hospital treatment. Age, C-reactive protein, presence of comorbidity and steroid treatment are significantly correlated with hospitalisation of low-risk patients with community-acquired pneumonia.