Abstract Background Myocardial performance is impaired in the first days of life in preterm infants but improves by day 5. Tissue Doppler imaging (TDI) is a novel and reliable means of assessing myocardial performance. Objective To investigate myocardial performance using TDI and shortening fraction (SF) in preterm infants of different gestational age groups and serial changes in these parameters in first four weeks of life. Study design Infants less than 36 weeks of gestation were divided into group 1 (24–27 weeks, n=8), group 2 (28–31 weeks, n=12) and group 3 (32–35 weeks, n=13). Infants with severe congenital malformations, a hypoxic insult at birth, and those on inotropic support were excluded. Echocardiograms were performed at 36–48 hours, 2 weeks and 4 weeks of life. Left ventricular (LV) SF, systolic (S′), early diastolic (E′) and late diastolic (A′) TDI velocities were assessed. We analyzed the data using a repeated-measures ANOVA. Results Thirty three infants underwent serial TDI and SF measurements. There was an increase in LV S′ (p=.02) and E′ (.01) velocities in group 2 , and in group 3 (p=.03 for S′ and p=.04 for E′), but no significant increase in group 1 (p=.48 for S′ and .32 for E′). At each study point, there was significant difference in myocardial performance between group 1 and 3 for each of the parameters (p<.05). There was no significant increase in SF over time in any of the groups. Conclusion We describe a serial increase in myocardial performance in infants of 28 weeks gestation and above. While there was no change in myocardial performance among the most extremely preterm infants, this may have been the result of small sample size of the group.