Objective: Handedness and self-care skills are important in occupational therapy. This research was done in schools of the eleventh zone of Tehran in 2002. This study took place in 61 normal students (32 right-handed, 29 left-handed) and 59 mental retarded student (40 right-handed, 19 left-handed) in preschool, first and second grade.

Materials & Methods: Average age for normal students was less than mental retarded students (P=0.001). Some data were taken from students through questionnaire and applying special tests for students got special data. Handedness and self-care skills were statistically compared between the two groups and relationship between them was calculated.

Results: There was a significant difference between the mean grip strength of right and left hand in right-handed normal students (P=0.001) but not in left-handed students (P= 0.234). There was significant relationship between self-care skills and grip strength in normal and mental retarded students (P=0.001). The difference of correlative comparison between manual skills and self-care skills was more than significant in mental retarded students than normal students (P<0.05).

Conclusion: In this study correlation between handedness and foot preference was more than the correlation between handedness and eye preference. There are significant relationships in comparing right-handed and left-handed in normal students based on birth rank (P=0.00l) but there aren't significant difference based on history of left-handed in family (P=0.963). It is recommended to evaluate and determine the handedness by means of many aspects like strength and handwriting alone is not enough.