Cardiovascular involvement was studied in 50 patients with serologically proved leptospirosis. Twelve (24%) patients had dyspnoea and 18 (36%) had transient hypotension during the illness. None of them had cardiac enlargement, development of new murmur or pericardial rub. Various electrocardiographic abnormalities occurred in 70 percent of patients. Atrial fibrillation was the most common major arrhythmia (14%). Conduction system abnormalities were seen in 36 percent of patients. T-wave changes were observed in 30 percent of patients. Left ventricular function as assessed by echocardiography and Doppler examination was normal. Three (6%) patients died due to renal failure. In conclusion, even though ECG abnormalities were frequently seen in leptospirosis, there was no data to support associated left ventricular dysfunction. Dyspnoea and hypotension occurring in patients of leptospirosis must be due to a noncardiac mechanism.