Background: Premature birth and postpartum hospitalization can hurt the father-newborn bonding and self-efficacy.Aim: To investigate the effect of fathers' involvement with premature newborns on paternal-infant bonding and self-efficacy.Methods: his was a nonrandomized clinical trial. Eighty fathers of hospitalized newborns in the neonatal intensive care unit were selected by convenience sampling method and divided into two groups. Fathers were trained on the developmental care of their newborn babies. The training was started through simulations and then at the bedside of the newborn. Newborns who were admitted to one of the Neonatal Intensive Care Unit (NICU) at Arash hospital (Tehran University of Medical Sciences). The study was conducted in 2017. Pre-and post-intervention outcomes were collected using the Parent to Infant Bonding Scale (Originally: Mother to Infant Bonding Scale) and the Perceived Maternal Parenting Self-Efficacy tool. The scale scores range from 0 to 27. A high score indicates worse bonding. Data were analyzed using independent t-test, paired t-test, repeated measures ANOVA.Result: The mean ± SD of the scores of the bonding score was reduced by 2.3±2.17 in the control group and 5.27±2. 57 in the intervention group. A lower score represents a better bonding. The self-efficacy score increased in both groups; however, it was significantly higher in the intervention group. In the intervention group increased by 8.85±5.046, and in the control group, it increased by 1.27±3.31.Implications for Practice: Developmental care by fathers can improve the father-infant bonding and increase the paternal self-efficacy for the care of the high-risk newborn.