Objective: Handwriting difficulty is a common problem in mentally-retarded students. This article investigates the relationship between handwriting and spatial analysis.

Materials & Methods: One hundred and twenty six mentally- retarded students (53 girls and 73 boys) ranging from 9 to 19 years old from two exceptional children schools in Shahr-e-Rey participated in this cross – sectional and descriptive survey. A handwriting check-list made by the researcher along with the subtest of designing with cubic from Wechsler scale (WISC-R) was executed on all of the students. Data was analyzed by using Independent T-test, U-Man Witeny, Kruskal-Wallis and Spearman correlation coefficient.

Results: Correlation coefficient showed that there is a significant relationship between handwriting scores and spatial analysis scores (r=0/305, P<0/0001). Also spatial analysis has significant relationship with size of letters in relation with each other (P<0/007), with size of handwriting (P<0/0001) and with writing on the line (P<0/002).

Conclusion: In order to developing handwriting legibility of mentally- retarded students in factors: size of letters in relation with each other, size of handwriting and writing on the line, the therapists must train mentally-retarded students with spatial analysis exercises.