ABSTRACTThis research was planned to determine the effect of breastfeeding on newborns' behavioral pain and comfort scores during heel blood collection. A pretest/posttest experimental-control group design was used. The research was conducted between August 2021 and June 2022. A total of 50 newborns, including 25 in each of the experimental and control groups, were included in the study. An Infant Descriptive Information Form, the COMFORTneo Behaviour Scale, the NIPS-Neonatal Infant Pain Scale, and the LATCH Breastfeeding Diagnosis and Assessment Tool were used in the study. The comfort behaviors and pain scores of infants in the experimental and control groups were evaluated during the heel blood collection process. The comparison of the comfort behaviors (comfort, pain, and distress), differences between pretest-posttest scores on the NIPPS pain score, and crying duration of the newborns in the experimental and control groups indicated a significant difference (p 0.05). The intra-group differences between the mean pretest and posttest scores of both the intervention and control groups were found to be statistically significant (p 0.05). Breastfeeding is an important nursing intervention for reducing procedural pain in newborns. The breastfeeding method reduces pain and distress and increases comfort for newborns during the heel blood collection process.HIGHLIGHTSBreastfeeding is an important nursing intervention for reducing procedural pain in newborns.The breastfeeding method reduces the pain and distress of the newborn during the heel blood collection process and increases comfort.Neonatal nurses can diversify the effectiveness of non-pharmacological methods in painful interventions by evaluating them with appropriate toolsKEYWORDS: Breastfeedingneonatal paincomfort behaviorsheel blood Disclosure statementNo potential conflict of interest was reported by the author(s).Authors contributionsİ.B. and AAK. conceived, designed the study and helped draft the manuscript. İ.B. and S.Ş.O. were involved in data acquisition and interpretation of data. İB. was the study statistician and contributed to the study design. S.Ş.O, P.K and H.U data collection, interpretation of data, preparation of the study report, manuscript writing, and reading and approving the drafts. İB, and A.A.K. participated in the interpretation of data, manuscript writing, critical review, and revising the manuscript.Additional informationFundingThe author(s) reported there is no funding associated with the work featured in this article.