Background: The health burden of diabetic nephropathy is exponentially increased by the constant and alarming increase of the incidence of both Type 1 and 2 diabetes mellitus. Aim: The study aimed to evaluate the effect of health educational program regarding nephropathy for mothers of children suffering from Diabetes Mellitus at Assiut City. Subjects and Method: Quasi-experimental (Pre-post-test) design implemented for 100 mothers of diabetic school-age children. Two tools included: Tool I: Part one: Personal and clinical data of children. Part two: Personal data of mothers. Tool II: Part one: Mothers' knowledge. Part two: Mothers' health-related practices. Results: Only 20% of school-age children's mothers had satisfactory knowledge regarding diabetic nephropathy in pretest. While raised significantly to 96% and 93% in posttest 1 and 2. Moreover, 35% of school-age children's mothers had satisfactory health-related practices regarding diabetic nephropathy in pretest. Whereas improved significantly to 82% and 91% in posttest 1 and 2. Conclusion: There was a significant improvement in the school-age children's mothers' knowledge and health-related practices regarding diabetic nephropathy after the educational program implementation. Recommendations: Continuing educational programs are needed to improve mothers' knowledge and practices toward better control of diabetic children.