Pneumonia is an important cause of death in childhood, especially in the infancy period. Since the respiratory and cardiovascular systems cannot be thought of independently, it is important to detect cardiovascular changes during pneumonia. We prospectively studied 50 children aged 2-24 months admitted to the hospital because of pneumonia in order to evaluate their cardiovascular findings with noninvasive methods. Patients were classified according to the World Health Organization (WHO) criteria of pneumonia, and evaluated by obtaining complete blood counts, serum electrolytes, renal and liver function tests, blood gases, creatinine kinase MB fraction (CK-MB), chest X-ray, electrocardiography (ECG) and echocardiography at the admission and after clinical recovery. Right ventricular systolic pressure (RVSP) was found to be high in 70% of patients and there was a correlation between the severity of the pneumonia and RVSP All patients had normal left ventricular dimensions and functions, but in 68% of them CK-MB was elevated. In these infants, T voltages in D1 derivation showed a significant rise with clinical recovery. Seven cases developed congestive heart failure, and three died. CK-MB was found to be high in all patients who died and in six of seven patients with congestive heart failure. Our findings suggest that myocarditis incidence in children with pneumonia may be higher than previously known. Since myocarditis can be a fatal disease, its detection is important by noninvasive techniques like ECG, echocardiography and cardiac enzyme measurements.