Objective: In this study we compared cardiothoracic ratio on chest radiography and left ventricular dimensions from echocardiography in patients with left heart valvular regurgitation. Methods: The studied population consisted of 107 patients (55 male, 52 female) aged 7 to 25 years (11.6±4.7 years) with isolated mitral or aortic regurgitation. Chest radiography and echocardiographic examination were performed on the same day in every patient. Results: Among 26 patients with moderate mitral regurgitation, cardiac enlargement was found in 4 (15%) patients on chest radiography, and in 7 (27%) patients on echocardiography. Among 25 patients with severe mitral regurgitation, cardiothoracic ratio was normal in 20 (80%) patients whereas cardiac enlargement was documented in 17 (68%) patients on echocardiography. Although there was no patient with cardiac enlargement (CE) on chest radiography in the groups of mild and moderate aortic regurgitation, 50% of patients in the group of severe aortic regurgitation had CE on chest radiography; cardiac enlargement was detected in 62% patients with moderate and 100% patients with severe aortic regurgitation on echocardiography. We found a good relation between the severity of valvular regurgitation, especially for aortic regurgitation, and CE on echocardiography; however only a poor relation was detected between the severity of valvular regurgitation and CE on chest radiography. Conclusion: In conclusion, prediction of severity of valvular regurgitation using chest radiography may lead to false interpretations and so, plain chest radiography may not be an essential part of the routine evaluation of such patients.