Three hundred twenty-seven patients with ovarian carcinoma were compared with matched controls to determine the association of parity and marital status with the development of ovarian cancer. Nulliparous women were found to have 2.31 times the risk of developing ovarian cancer as parous women. Unmarried women had 3 times the risk of developing ovarian cancer, but marital status was not established as a variable independent of parity. Almost 8% of patients with ovarian carcinoma had had hysterectomies when they were over 40 years of age. This study indicates that parity is an important consideration when determining whether a patient is at high risk for the development of ovarian carcinoma. Other epidemiologic variables are discussed in an effort to facilitate the judicious selection of patients for elective oophorectomy at the time of hysterectomy.