Background: Positioning is an important tool to improve the efficiency of respiratory function and it is one of the important nursing duties. Aim: of this study was to assess effect of right lateral position on oxygenation of premature infants after weaning from mechanical ventilation. Research design: A quasi-experimental research design was used Subjects and Setting: A convenient 60 premature infants within 2 hours after weaning from the mechanical ventilation were included in the study in neonatal intensive care unit (NICU) at Assiut University Children Hospital. They divided to two groups (the control and the study) Tools: Two tools were developed to collect data of the present study. Results: At the end of the 6th 20 minutes after weaning from mechanical ventilators mean ± SD SaO2 (%) of premature infants in the right lateral position was (95.90 ± 1.95) compared by (92.27 ± 2.41) among Premature infants in the control group. Statistically significant differences were found between the two groups related their PH, and respiratory rate. Conclusion: Premature infants placed on the right lateral position had higher SaO2 (%) and lower complications as breathing difficulty and /or apnea than others. Recommendations: Right lateral position should be used in the routine care of infants weaning from mechanical ventilation.