BACKGROUND: Pain management is an essential component of care for pediatric patients following surgery. Massage reduces self-reported postoperative pain in adults with heart disease but has received little attention in postoperative pediatric patients with complex congenital heart disease (CCHD). OBJECTIVES: The aim of the study was to evaluate the effectiveness of massage compared to a rest period on postoperative pain scores and physiological responses in infants with CCHD. METHODS: We used a two-group randomized clinical trial design with a sample of 60 infants with CCHD between 1 day and 12 months of age following their first cardiothoracic surgery. Both groups received standard postoperative care. Group 1 received a daily 30-minute restriction of nonessential caregiving (quiet time), and Group 2 received a daily 30-minute massage. Interventions continued for seven consecutive days. Pain was measured six times daily using the Face, Legs, Activity, Cry, Consolability Pain Assessment Tool (FLACC). Average daily doses of analgesics were recorded. Heart rates (HRs), respiratory rates (RRs), and oxygen saturations (SpO2) were recorded continuously. Daily averages, pre- and postintervention FLACC scores, and physiological responses were analyzed using descriptive statistics, generalized linear mixed models repeated measures, latent growth models, and/or regression discontinuity analysis. Fentanyl-equivalent narcotic values were used as a time-varying covariate. RESULTS: Adjusted pain scores were lower for the massage group on all days except Day 7. Overall, there were no group effects on level of pain or differential rate of change in pain. However, the massage group had lower daily pain scores with small to medium effect size differences, largest at Days 4, 5, and 6, and lower average daily HR and RR. There was little difference between groups in SpO2. Infants demonstrated immediate effects of massage, with HR and RR decreasing and oxygen saturations increasing. DISCUSSION: This study provides beginning evidence that postoperative massage may reduce pain and improve physiological parameters in infants with congenital heart disease. This nonpharmacological adjunct to pain management may provide a particular benefit for this population by reducing demand on the cardiorespiratory system.