Introduction: In infertile women stress can reduce the chance of treatment success. So relieving their stress during the course of treatment is very important. This study aimed to investigate the effect of relaxation on the outcome of infertility treatment. Methods: This is a semi-experimental study. It was done on 76 infertile women between 18 to 35 years old under treatment with IVF or ICSI, referring to Isfahan Fertility and Infertility Center. They were assigned into intervention and control groups by simple randomized sampling. Relaxation technique was performed for the intervention group in 12 sessions. Data was gathered by Newton`s infertility stress questionnaire before and after the intervention (before pregnancy test). Data was analyzed by spss16 using paired t-test, chi-square and mann-whitney tests. Results: Statistical analysis showed no significant differences in demographic – fertility characteristics in intervention and control groups. Chi-square test showed that the percentage of success (positive pregnancy test) was significantly higher in the intervention group (p=0.006). Discussion: Relaxation technique can lead to increased success in outcome of pregnancy (positive pregnancy test) after IVF or ICSI.