Twenty-five cases of patients with pure immature teratoma of the ovary, accrued from the Connecticut Tumor Registry from 1969 to 1984, were reviewed. Two patients had grade 1 tumors, twelve had grade 2 tumors, and eleven had grade 3 tumors. The majority of patients (23) were stage I at the time of initial surgery. Twenty-one of the twenty-three patients were treated with some form of unilateral adnexal surgery with or without adjuvant combination chemotherapy (VAC). Two of the twenty-three patients were treated with total abdominal hysterectomy/bilateral salpingooophorectomy (TAH/BSO) with the addition of either VAC chemotherapy or radiation therapy. Recurrence occurred in two patients, both of whom had grade 3 tumors and were subsequently treated with surgical resection plus VAC chemotherapy. One patient, who recurred after initial therapy with unilateral salpingo-oophorectomy (USO) plus VAC chemotherapy, was successfully treated with surgical resection and further chemotherapy. Two patients were stage III at the time of initial surgery, one of whom was treated with USO plus adjuvant combination chemotherapy and radiotherapy. The other patient was treated with TAH/BSO plus VAC chemotherapy. In our series, no patient died from immature teratoma (one patient died from advanced breast carcinoma). It is reasonable to withhold chemotherapy from patients with stage I, grade 1 and 2, immature teratoma which may be treated initially with conservative surgery. The risk of recurrence in patients with grade 3 tumors warrants the addition of further chemotherapy.