Vaginal infections are the most common gynecological diseases and one of the causes of sexual dysfunction. In more than 50% of patients, sexual dysfunction is twice as common. Evaluation of the treatment outcome of vaginal infections can be effective in identifying factors related to the sexual function. This is a descriptive-observational study that included patients referred to Imam Sajjad Shahriar Hospital during 2017-2018. Patients that met the inclusion criteria (with vaginal infections of Candida, Gardnerella and mixed infections – Candida and Gardnerella – Mixed group) completed the Female Sexual Function Index (FSFI) questionnaire before and one month after treatment. Data were analyzed by SPSS 16, paired t-test, ANOVA, and multiple regression. P-value <0.05 was considered significant. After the treatment of vaginitis, there was a significant increase in all aspects of the FSFI questionnaire. The mean and standard deviation of sexual function of women before and after treatment were 18.26 ± 4.36 and 26.27 ± 4.97 in the Candida group, 20.06 ± 4.94 and 25.87 ± 5.32 in the Gardnerella group, and 19.69 ± 4.25 and 27.05 ± 5.12 in the Mixed group. Prior to treatment in the Mixed and Gardnerella group, the most important sexual dysfunction was related to the dyspareunia component, while in the Candida group, the most important sexual dysfunction was related to the desire component. After treatment, the components of dyspareunia in the Mixed and Gardnerella group and the orgasmic component in the Candida group showed the greatest improvement. The regression test showed that the effect of age, body mass index and duration of sex on sexual function was significant (P <0.05). Duration of the disease had the greatest impact on sexual dysfunction, and after treatment of the disease, sexual function improved significantly. Proper diagnosis and treatment are effective in improving women’s sexual function. The results of this study can be promoted to midwives and gynecologists.