Objective: To assess the reference values of M-mode echocardiographic measurements in healthy newborns according to body weight. Methods: From January, 2008 to June, 2008, a total of 250 - 130 female and 120 male - term healthy newborns were included in the study. M-mode echocardiographic measurements were recorded by a paediatric cardiologist in accordance with the American Society of Echocardiography recommendations. Right ventricular anterior wall end-diastolic thickness, right ventricular end-diastolic diameter, interventricular septum end-diastolic thickness, left ventricular end-diastolic diameter, left ventricular posterior wall end-diastolic thickness, interventricular septum end-systolic thickness, left ventricular end-systolic diameter, left ventricular posterior wall end-systolic thickness, aortic root dimension, left atrium dimension, left ventricular ejection, and shortening fraction were measured. Results: The values of echocardiographic measurements revealed a good correlation with body weight. When body weight increased, the measured values also increased in parallel. The measured values were not influenced by gender. Ejection and shortening fraction parameters did not change with body weight and gender. Conclusion: In this study, normative values related to body weight for cardiac chambers and wall thickness were determined in healthy newborns. These reference values can be used to evaluate whether newborns have normal or abnormal echocardiographic measurement.