Objective: To study the effect of computer–assisted instructional software on counting, addition and subtraction learning for students with learning disability. Method:  20 students with dyscalculia (7-8 years old) were randomly selected and matched into a quasi-experimental control group design. Results: The results of Iranian version of Key Math test (Mohamad Esmaeel and Hooman, 2002) scores of the two groups by t-test showed that: application of the designed instructional software has a significant effect on counting, addition and subtraction learning for students with dyscalculia. Conclusion: This software can be considered as an appropriate means for teaching arithmetic operations to these students.