Objective: This article investigates the relationship between visual-motor integration and handwriting. Method: From 157 mentally retarded students studying in the exceptional children schools in Shahr-e Rey, 126 mentally retarded students (53 girls and 73 boys) ageing from 9 to 19 participated in this study. A researcher-made handwriting checklist and the Developmental Test of Visual-Motor Integration (VMI) were used to assess all of the students. Result: The correlation coefficient showed that there exists a significant relationship between handwriting scores with VMI scores(r = 0/472, p<0/0001). The most common impaired legibility component in the sample was “interruption during writing words” with 81% and the least common was “spacing between letters and words” with 34.9%. Conclusion: This study stresses that visual-motor integration in mentally retarded children must be evaluated by the related professional.