Background and Objectives: Infants born preterm are particularly vulnerable to procedural stress and pain exposure during neonatal intensive care unit stay at a time of rapid and complex brain development. The low tactile threshold in preterm infants when they are in NICU renders them more vulnerable to the effects of repeated diagnostic and therapeutic invasive procedures. The aim of present study was to assess the effect of breast milk feeding on pain during heel stick procedure among late preterm neonates. Materials and methods: A randomized clinical trial was adopted with random sampling to select 128 late preterm neonates who fulfilled the inclusion and exclusion criteria. Infants were randomized to control and experimental groups. For the neonates in the control group, PIPP assessment had done 15 minutes before heel stick and repeated 5 and 15 minutes after the procedure. For the neonates in the experimental group, baseline pain assessment had done 15 minutes before heel stick procedure. Direct breast milk feeding or Paladai feed of 5 ml expressed breast milk of own mother provided 5 minutes before heel stick procedure. Pain score assessed 5 minutes and 15 minutes after the heel stick procedure using Premature Infant Pain Profile (PIPP). For analysing the data, descriptive statistics (frequency, percentage, median, and interquartile range) and inferential statistic (Mann Whitney u test, Pearson chi-square) were used. All the statistical significance were carried out at 5% level of significance. Result: The comparison of median pain scores between control group and experimental group, 15 minutes before and 5 minutes and 15 minutes after heel stick procedure showed that 15 minutes before heel stick procedure median pain score in control group and experimental group were 1 (1, 1) and 1 (0.5, 1) respectively with a statistical significance p=0.864. 5 minutes after heel stick procedure in control group median pain score was 6 (5, 6), where as in experimental group median pain score was 3 (2, 4) with a statistical significance of p<0.001. 15 minutes after heel stick procedure in control group and experimental group median pain scores were 2 (2, 3) and 2(1, 2) respectively with a statistical significance of p<0.001. Conclusion: The study concluded that breastmilk feeding is effective in reducing the pain during heel stick procedure among late preterm neonates. Breastmilk feeding can be adopted as a cost effective and non-pharmacological measure during heel stick procedure among late preterm neonates.