Trinidad and Tobago is an island-state in the Caribbean with a size of 5 128 square kilometers and a population of 1.3 million. Pneumonia is a leading cause of death in Trinidad. This project determined the frequency of Legionella pneumophila in patients with pneumonia, investigated the relationship between pneumonia and selected risk factors. Serum and demographic data were collected from 123 patients, diagnosed with pneumonia. Sera were tested for L pneumophila Ig G/M/A and IgM. All analyses were done using the SPSS statistical package. Of a total of 123 serum samples tested, 39 (31.7%) were positive for L pneumophila IgM/G/A while 2 (1.6%) were positive for IgM only. Hospitals, gender and ethnicity did not significantly (p > 0.05; χ2) affect the seroprevalence of L pneumophila. Overall, the prevalence of L pneumophila assayed was not significantly (p > 0.05, χ2) affected by co-morbidities.