The CURB-65 score (Confusion, Urea > 7 mmol x L(-1), Respiratory rate > or = 30 x min(-1), low Blood pressure, and age > or = 65 yrs) has been proposed as a tool for augmenting clinical judgement for stratifying patients with community-acquired pneumonia (CAP) into different management groups. The six-point CURB-65 score was retrospectively applied in a prospective, consecutive cohort of adult patients with a diagnosis of CAP seen in the emergency department of a 400-bed teaching hospital from March 1, 2000 to February 29, 2004. A total of 1,100 inpatients and 676 outpatients were included. The 30-day mortality rate in the entire cohort increased directly with increasing CURB-65 score: 0, 1.1, 7.6, 21, 41.9 and 60% for CURB-65 scores of 0, 1, 2, 3, 4, and 5, respectively. The score was also significantly associated with the need for mechanical ventilation and rate of hospital admission in the entire cohort, and with duration of hospital stay among inpatients. The CURB-65 score (Confusion, Urea > 7 mmol x L(-1), Respiratory rate > or = 30 x min(-1), low Blood pressure, and age > or = 65 yrs), and a simpler CRB-65 score that omits the blood urea measurement, helps classify patients with community-acquired pneumonia into different groups according to the mortality risk and significantly correlates with community-acquired pneumonia management key points. The new score can also be used as a severity adjustment measure.