Sexual dysfunction can be a long-term issue for women with gynecologic cancer. This study assesses the extent of sexual and marital dysfunction women face following treatment of a gynecologic cancer. A cross-sectional study of women with gynecologic cancer was conducted using a 181-item survey. Sexual dysfunction was measured by change in the Female Sexual Function Index score; marital dysfunction was measured by change in Intimate Bond Measure from prediagnosis to posttreatment. Paired t tests and Fisher exact test were used to compare women with dysfunction to those without dysfunction. Three hundred twenty women were enrolled (mean age, 56.0 SD, 12.0 years). Among all women, sexual function declined from a score of 21.3 (SD, 10.4) prior to 15.3 (SD, 10.2) (P < 0.001), and sexual activity decreased from 6.1 (SD, 6.8) to 2.6 (SD, 4.9) times per month following treatment (P < 0.001). Among the 208 women who were sexually active at the time of study, sexual dysfunction after treatment was associated with younger age (50.9 SD, 11.7 years to 57.3 SD, 12.3 years), ovarian (40.7% vs 30.7%) or cervical (21.0% vs 10.2%) cancer diagnosis, chemotherapy treatment (72.8% vs 50.4%), and being in a relationship (97.3% vs 82.7%). Among women in relationships, 27% experienced marital dysfunction. Women who are younger, have an ovarian or cervical cancer diagnosis, receive chemotherapy, or are in a committed relationship are at particularly high risk of sexual dysfunction. These women should be provided information about the risks associated with their cancer treatment.