The study aim was to evaluate the long-term efficacy of Internet-based cognitive behavioral therapy (CBT) for sexual dysfunctions in 84 breast cancer survivors. The positive effects of the intervention on overall sexual functioning, sexual desire, sexual arousal, vaginal lubrication, discomfort during sex, sexual distress, and body image observed immediately posttreatment were maintained at three- and nine-month follow-ups. Although sexual pleasure decreased during follow-up, it did not return to baseline levels. Our findings provide evidence that Internet-based CBT has a sustained, positive effect on sexual functioning and body image of breast cancer survivors with a sexual dysfunction.