Objective: This research is an evaluation for the efficacy of a mathematics concepts teaching for students with Down syndrome (DS). Method: utilizing an experimental pretest-post test control group design 30 students with DS were recruited and matched in Tehran. A researcher made test, demographics inventory, and Leither International Performance Scale were used to assess the related variables. Results: Two and three ANOVA revealed that using the designed software in basic teaching concepts (P=0.000<0.001) and counting numbers (p= 0.009 <0.01) in students with DS is more effective than traditional method, and is similar in recognizing numbers. Conclusion: Accordingly, this study suggests that the software is helpful in teaching mathematics to students with DS.