Objective: The effects of hemsball game skills development program on the motor proficiency level of children in the 12-16 age group with mild and moderate intellectual disabilities (ID) have been examined in this study. Method: A total of 50 (25 experimental group +25 control group) students, 23 of which had mild intellectual disabilities (ID) and 27 with moderate ID studying in special education classes in the schools in Afyonkarahisar province in Turkey participated in the study. While no training was given to the control group, the students in the experimental group were subjected to 60 min of applications involving a basic hemsball training program per day for 3 days per week throughout 12 weeks. Bruininks-Oseretsky Test of Motor Proficiency (BOT-2) sub-tests (balance, bilateral coordination, upper-limb coordination) were applied twice, once before starting the program (pre-test) and once after the program was completed (post-test). The obtained data were tested with paired-samples t-test and independent-samples t-test. Result and Conclusion: As a result of the study, it was noted that the application of the hemsball game skill development program had incurred significant differences between the experimental and control group according to the post-test as well as the pre-test and post-test for the experimental group which were positive. However, it was determined that the application was more effective in students with moderate level ID than students with mild ID.