In this research, stevia and inulin was used as sugar and fat replacer in dietetic ice cream formulation, respectively. Ice cream formulation with stevia (0-100%) and inulin (0-85%) was optimized using Response Surface Methodology. Dependent variables included specific gravity (SG), viscosity, overrun, first drop and melting. The results showed that SG had converse relation with replacing stevia and positive correlation with replacing inulin. Viscosity was decreased by increasing substitution of stevia up to 100%, while increasing replacement of sucrose with stevia led to increase overrun. All levels of substitution of stevia and inulin led to significant increase of hardness. The lowest melting rate was observed in sample containing 100% stevia and sample containing 0% inulin. Optimum content of stevia and inulin was determined 42% and 62.9% respectively, in Dietetic ice cream. In sensory evaluation there was no significant difference in total acceptance between diet and control sample that contained 15% sugar and 10% fat (P>0.05) but dietetic ice cream had lower score for intensity of crystalline and coldness. The calorie of diet ice cream was 28% lower than control sample.