Background: Lactose intolerance is a predominant indicator of under nutrition in children. They have abdominal discomfort, burping, and diarrhea whenever they consume dairy. Aim of the study: Assess mother's perception regarding their children with lactose intolerance. Design: A descriptive analytical design was used to conduct this study. Setting: The study was conducted at nutritional outpatient clinics at pediatric Ain Shams hospital affiliated to Ain Shams University, Cairo, Egypt. Sample: Purposive sample composed of 291 mothers, having children less than five years, confirmed diagnosis with lactose intolerance, attending to nutritional clinic for follow- up, free from any co-morbid diseases. Tools of data collection: three tools were used to collect the data 1^st tool: Interviewing questionnaire include socio demographic characteristics of mothers and their children, Mothers' and child health history, knowledge of mothers regarding lactose intolerance, and mothers' reported practices toward their children with lactose intolerance. 2^nd tool: Attitude scale of Mothers' toward their Children with lactose intolerance.  3^rd tool: Anthropometric measurements of Children. Results: More than three quarters of the studied mothers were at unsatisfactory level of total knowledge, more than half of them were at poor level of total reported practice, and more than half of the studied mothers were negative attitude regarding their children with lactose intolerance. Conclusion: There were statistically significant positive correlation between total mothers' knowledge, total reported practice and total attitude toward their children with lactose intolerance. Recommendations: Developing and implementing of health education programs to increase their knowledge, practices and their attitudes toward their children with lactose intolerance.