INTRODUCTION: Orgasmic dysfunction in women is characterized by persistent or recurrent delay in or absence of orgasm following a normal sexual excitement phase. Research has shown that almost two thirds of women have concerns about their sexual relationship. Sexual dysfunction has many problems for couples; some researchers found that up to 67% of divorces related to sexual disorders. OBJECTIVE: The aim of this cross-sectional study was to assess the prevalence and related factors of anorgasmia among reproductive age Iranian women. METHODS: This study was conducted in 2006-7 in Hesarak, Karaj, Iran. A total of 1200 women were randomly recruited to the study. Sexual satisfaction questions were prepared according to the Enrich Sexual Satisfaction Questionnaire. Orgasms were assessed according to the relevant questions in the Female Sexual Function Index (FSFI) questionnaire. The data were analyzed using SPSS version 11; Chi-square, Mann-Whitney and independent t-test were used for statistical purposes. RESULTS: This study showed that the prevalence of anorgasmia among Iranian women in Hesarak, Karaj, was 26.3%. There was a significant difference between the anorgasmic and normal orgasm groups regarding the women's age, age at marriage, duration of marriage and education during puberty (p<0.05). Some psychological factors, e.g. anxiety, fatigue, pain, feeling of guilt, anti-masculine feelings and embarrassment in sexual relationships were higher in the anorgasmic group (p<0.001). DISCUSSION: The results of this study showed that the prevalence of anorgasmia in Hesarak is high and most of the anorgasmic women were highly unsatisfied with their sexual relationship compared to the normal orgasm group. CONCLUSION: The prevalence of anorgasmia among Iranian women in Hesarak, Karaj, is high and some socio-demographic and psychological factors have a strong relationship with anorgasmia.