We retrospectively reviewed the medical records and chest radiographs of 118 patients who presented during January 1998 to October 2002 at Songklanagarin Hospital in Hat Yai, Songkhla Province, Thailand who had a high serum immunofluorescent assay titer for leptospirosis. Twenty-nine of 118 (24%) patients had abnormal chest films. Nearly all of these patients had respiratory symptoms and needed oxygen therapy (93% and 90%, respectively). Forty-eight of the 118 (40%) had respiratory symptoms, but only 27/48 (56%) had abnormal radiographs. Twenty-one of the 28 (75%) and 18/27 (67%) who had abnormal chest radiographs had coexisting impaired renal function or jaundice, respectively, whereas 21/69 (30%) of the patients who had impaired renal function and 18/55 (33%) of the patients with jaundice had abnormal radiographs. There were 6/27 (22%) patients who had abnormal chest radiographs without renal or liver impairment. The most common finding on the abnormal chest radiograph was bilateral diffuse air space disease, which resolved within 7 days. No permanent lung damage was seen. The patients who had an abnormal chest radiograph needed longer hospitalization, than those without an abnormal chest radiograph (average 12 days and 5 days, respectively).