Background: Non-synostotic Plagiocephaly is acquired cranial asymmetry that has a significant impact on the cosmetic appearance of the infant's head and great concern to parents. Therefore, this study aimed to investigate the effect of conservative nursing interventions to mothers for prevention of Nonsynostotic Plagiocephaly and its efficacy on their infants' motor development. Design: Quasi-experimental was utilized. Settings: This study was carried out at Ash-moon Health Office in El Menoufia Governorate. Sample: A purposive sample of 75 mothers & their infants who attended in Menoufia the previously mentioned setting from the period of January to December 2021. Tools: Data were collected using the three following tools: Tool one: Structured interviews questionnaire for mothers was used to assess mothers' knowledge about Non-synostotic Plagiocephaly. Tool two: Mothers' reported practices about prevention of Nonsynostotic Plagiocephaly. Tool three: Clinical observation sheet for infants. Results: There were highly statistically significant differences improvement of mother's knowledge and reported practices mean scores about prevention of Non-synostotic Plagiocephaly in the post and follow-up tests p ˂ 0.001. There were significantly differences found in the mean scores of infants' motor development. Conclusion: The conservative nursing interventions had significant effect on improving mother's knowledge and reported practices regarding prevention of Non-synostotic Plagiocephaly & consequently on their infants' motor development. Recommendation: Awareness educational program should be applied on a regular base to develop the knowledge and practice of parents about the prevention of Non-synostotic Plagiocephaly among their infants.