['Cardiovascular compromise is increasingly recognized in preterm infants. Currently, echocardiography is the best tool to assess myocardial contractility and guide management. Elevated levels of cardiac troponin T (cTnT) and N-terminal-pro-B type natriuretic peptide (NTpBNP) are associated with poor myocardial contractility and low cardiac output in adults.', 'To examine the range of cTnT and NTpBNP in preterm infants, to correlate NTpBNP and cTnT with echocardiographic markers of cardiac function and to assess the influence of antenatal and postnatal factors on these biochemical markers.', 'Plasma concentrations of cTnT and NTpBNP were measured in infants <1500 g at 12 h of age. These were correlated with simultaneous echocardiographic measures of myocardial function and output. Antenatal data, infant demographics and postnatal characteristics were prospectively recorded.', 'A total of 80 infant had samples taken and echocardiography performed. Their median (interquartile range) cTnT and NTpBNP values were 0.20 microg l(-1) (0.11 to 0.40) and 1273 pmol l(-1) (664 to 2798), respectively. There was a significant inverse correlation between cTnT and echocardiographic markers of myocardial function and stroke volume. NTpBNP significantly correlated with left atrial to aortic root ratio (LA:Ao). There was a weaker but significant negative correlation between NTpBNP and left ventricular (LV) function. The assays were not influenced by gestation, birth weight, gender or mode of delivery.'] Do cardiac troponin T and N-terminal-pro-B type natriuretic peptide reflect myocardial function in preterm infants?