Background: Maintaining personal hygiene behaviors among mentally retarded children enhances their physical and emotional well-being. Aim: The present study aimed to evaluate effect of personal hygiene program on knowledges and practices of mentally retarded students at El-Fikreya schools in Minia Governorate. Design: Quasi-experimental design was utilized with pre/posttest. Setting: The study was conducted in all schools for mentally retarded students in Minia governorate, which were: El-Fikreya school in Minia city, in Matay district and in Malawy district. Sample: A convenient sample consisted of 53 mentally retarded girls. Tools of data collection: one tool was used: A mentally retarded student's structured interview questionnaire to assess personal hygiene knowledges and self reported practices. Results:  Mean age of studied students was 12.4 ± 3.2 years, mean Intelligence Quotient (IQ) was 56.9 ± 6.4 score. Their knowledge score and self-reported practices about personal hygiene were improved from 9.4% and 15.1% respectively in pre- program to 43.4% and 71.7% immediately after program and 22.6% &54.7% after one month of program implementation. Conclusion: there were improvements of knowledges and self-reported practices about personal hygiene of studied students after educational program. Recommendation: sustainable school health education program with active involvement of school teachers should be conducted in each school.