The assessment of motor function in children is one aspect of determining functional performance used by occupational therapists. In order to evaluate motor abilities, it is necessary to use valid and reliable assessments. The Bruininks-Oseretsky Test of Motor Proficiency (BOTMP) has been frequently used by occupational therapists in different countries to assess the fine and gross motor skills of children. However, the BOTMP was standardised on American children and no attempt has been made to investigate the applicability of this normative data to children of other countries. Furthermore, some therapists have expressed their concern about the categorisation of the test into fine and gross motor composites. This study aims to examine the applicability of the BOTMP to children in Iran and to investigate the factor structure underlying the BOTMP subtests. The BOTMP was administered to 170 Iranian children aged 4H and 6V^ years. For the 5 year old group significant differences in performance were found between Iranian and American standardisation samples on the following subtests of the BOTMP: bilateral coordination, strength, response speed, visual motor control, and running speed and agility. While 5 year old Iranian children performed better than the American standardisation sample on the bilateral coordination, strength, and visual motor control subtests, American children scored higher on the response speed as well as running speed and agility subtests. Six year old American children performed better than Iranian children on the response speed, balance, and running speed and agility subtests. However, American children did not perform as well on the strength, and visual motor control subtests. There were no significant differences between the 6 year old Iranian children and the normative American sample on the following subtests: the upper limb speed and dexterity, upper limb coordination, and bilateral coordination. No significant gender differences were found in either age group of Iranian children on any of the BOTMP subtests. Further, significant differences were found between the performance of the two age group of Iranian children on all the BOTMP subtests except for the balance subtest. Finally, one strong factor underlying the structure of the BOTMP subtests was identified. This factor could be labelled "general motor proficiency". Clinical implications and future research areas have been highlighted.