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.