Objective: The purpose of the present study was to determine the prevalence of arithmetic disorder among school children in grades two to five in Ardebil. Method: Taking into consideration the proportion of students in the Ardebil 1 and 2 districts, 6 schools from district 1 and 4 schools from district 2 were selected that comprised a total of 1171 children from grade 2 to grade 5. In order to examine the children’s performance in arithmetic, a Standardized Battery of Arithmetic was used.  Results: Findings revealed that 44 children scored two standard deviations below the mean and were diagnosed as having arithmetic disorder and a prevalence of 3.76 was estimated. The rate of prevalence of arithmetic disorder among boys was twice as among girls. The prevalence of arithmetic disorder in elementary school children of Ardebil is in agreement with some other similar studies in other places. Conclusion: This considerably high rate of arithmetic disorder prevalence among children calls for more rigorous educational interventions.