To prospectively compare a modified pneumonia severity scoring system, SMARTACOP, with other severity scores in patients presenting with pneumonia to the emergency department (ED) of a tertiary referral hospital in tropical Australia. We conducted a prospective observational study of adult patients presenting with radiologically confirmed pneumonia over a 12-month period. The sensitivity of risk stratification scores were assessed against the need for intensive respiratory or vasopressor support (IRVS). There were 367 ED attendances for pneumonia of whom 77.1% were admitted to hospital, 10% required intensive respiratory or vasopressor support and 2.8% died. Mean age was 50.0 years, 52% were men and 59% were Indigenous. The sensitivity of a SMART-COP score ≥3, a SMARTACOP score ≥3 and a pneumonia severity index (PSI) class ≥3 for predicting IRVS was 97%, 97% and 78% respectively. We found no significant advantage of the SMARTACOP over the SMART-COP score for the prediction of intensive respiratory or vasopressor support, but both scores significantly outperformed PSI. The SMART-COP score should replace the PSI in tropical Australia and should be assessed in other tropical areas for pneumonia risk stratification in emergency departments.