Preterm newborns develop a coordinated sucking and swallowing depending upon their gestational age and maturation of their respiratory, digestive and neurological systems. However, criteria to determine the best time for initiation of breastfeeding is an important challenge for physicians, nurses, and parents. Aim: the study aimed to investigate the effect of oral sensory stimulation program with expressed breast milk on breastfeeding outcomes of preterm newborns Design: a quasi-experimental study design was utilized. Setting: The study was conducted at neonatal intensive care unit of Cairo University Children Hospital, Cairo, Egypt. Sample: The study sample composed of 80 preterm newborns with gestational ages ranging between 32 and 36 weeks. Preterm newborns were selected for the research based on inclusion criteria and were allocated randomly to one of two equal groups (control group 40 and intervention group 40). Study Tools: Included, (1) The newborn's medical record (2) feeding assessment sheet (3) preterm infant breastfeeding behavioral scale. The preterm newborn in the study group received an oral sensory stimulation program with expressed breast milk and the control group received only routine hospital care. Results: There was statistically significant difference between preterm newborns in control and intervention groups regarding to transition time from gavage feeding to full breastfeeding, weight gain and length of hospital stays. There was statistically significant difference between the preterm newborns in control and intervention groups in all six items of preterm infant breastfeeding behavioral scale in the first attempt of breastfeeding, second day and before discharge. There were no statistically significant differences between the control and intervention groups regarding respiratory rate and oxygen saturation before the beginning of the study, after 5 days and on discharge. Conclusion: Providing an oral sensory stimulation program with expressed breast milk had a highly statistically significant effect on breastfeeding outcomes of preterm newborns including, enhancing breastfeeding readiness behavior, decreasing the transition time from gavage to full breastfeeding, increasing weight gain, and subsequently reducing length of hospital stays. Recommendation: Set an oral sensory stimulation program with expressed breast milk as a part of routine nursing care for preterm newborns in neonatal intensive care units.