Aim To determine the effects of two different methods, breastfeeding and heel warming, during heel stick procedures on pain levels in healthy term neonates. Methods This study was a prospective, randomized controlled trial. The sample of the study consisted of 150 healthy newborns who matched the case selection criteria and were brought to the nursery for the heel stick procedure. Fifty neonates were randomly assigned to each group: breastfeeding (n = 50), heel warming (n = 50), and control (n = 50), using computer-based randomization. The study data were obtained using an Information Form and the Neonatal Infant Pain Scale (NIPS). Results The pre-procedural pain scores of the breastfeeding group (mean 4.44 SD 1.21 seconds) were lower than in the heel warming (mean 6.10 SD 1.07 seconds) and the control group (mean 6.42 SD 0.91 seconds) (P < 0.01). Both the total crying time and the first calming time of the breastfeeding group were shorter than the heel warming and control group. The first calming time of the heel warming group was shorter than in the control group. Conclusions Both breastfeeding and heel warming are effective in reducing the calming time during heel stick procedures. However, breastfeeding is more effective than heel warming in reducing pain during heel stick and should be preferred as the first choice.