Background and Objective : Today’s children will make tomorrows society. Due to the pivotal role of nutrition in health and growth, it is important to great care be taken by the parents to understand the best method of nourishment in the most sensitive period of children. Therefore this project was designed to evaluate the knowledge of mothers who refer to the Khoy health centers for there less than 3 years old children for assessment of physical growth and health status.  Material and Methods : The research is a descriptive cross–sectional study which was conducted during three months during 2002 and mothers of under 3 years old children who refer to the health centers of Khoy were the target population. 70 mothers of under 3 years old children were randomly selected from research population. Data were collected by a questionnaire which was designed by researchers and were statistically analyzed by using SPSS software. Results: Based on the research findings, 51.4% of mothers were 24 years and less and 45.7% of them did not finished high school. 5.7 %of mothers did not work out and 81.4% of them breast-feed their children. 50% of mothers had an average level of awareness about the nourishment and 57.1% of mothers had an average level of awareness about the physical growth of the children under 3 years old.  Conclusion : However, the knowledge of mothers in this study was at median level, but the improvement of this knowledge regarding the status of their children is important in physical growth and health status of next generation.