Abstract Background: Hypoactive Sexual Desire Disorder (HSDD) is a very prevalent sexual problem, with limited options for treatment. Given that psychological factors are major contributors to the disorder, a therapy such as Cognitive-Behavioral Therapy (CBT) may be useful to treat HSDD. Objective: To evaluate the effects of group CBT on women with HSDD. Method: Clinical trial randomized study with 106 women diagnosed with HSDD, who were divided as follows: Group 1 (n = 53) underwent group CBT for 8-weeks, and Group 2 (n = 53), were put on a waiting list and used as a control group. Sexual function was assessed by the Female Sexual Quotient (FSQQ) at the initial interview and after 6-months. Mann Whitney test was used for group comparison. Main Outcome Measures: demographics, education, sexual history, FSQQ and its domains for sexual function assessment. Results: Both groups had similar characteristics regarding sexual response, self-image, and relationship with a partner at the initial interview. Women undergoing therapy showed significant improvement in sexual function when compared with the control group. The overall FSQQ result showed an average growth of 18.08 points (95% CI 12.87‒23.28) for the therapy group against a decrease of 0.83 points (95% CI 3.43‒1.77) for controls (p < 0.001). The five domains of the questionnaire also exhibited significant improvement in the therapy group: desire and interest (p = 0.003), foreplay (p = 0.003), excitation and tuning (p < 0.001), comfort (p < 0.001), and orgasm and satisfaction (p < 0.001). Conclusion: Group CBT was shown to be an effective tool for treating HSDD.