Between 1956 and 1990, 775 women were treated for Hodgkin's disease at The University of Texas M.D. Anderson Cancer Center. Of these, 25 (3.2%) were pregnant at diagnosis. Seven of these women were in the first trimester, 10 in the second, and eight in the third. Prior to treatment, three women in the third trimester had normal deliveries, and six patients in the first trimester had abortions. Sixteen patients received radiotherapy for supradiaphragmatic presentations during their pregnancies. All these patients had nodular sclerosing Hodgkin's disease: Two had clinical stage IA presentations and 14 had clinical stage IIA. In two patients radiotherapy (35 Gy) was limited to the neck, three patients were treated definitively to the neck and mediastinum (40 Gy), and 11 patients received mantle irradiation (40 Gy). Four to five half-value layers of lead were used to shield the uterus during radiotherapy. The dose to the fetus was estimated individually in nine patients, using a combination of an Alderson-Rando and a water phantom. The estimated total dose to the mid-fetus ranged from 1.4 to 5.5 cGy for treatment with 6 MV photons, and from 10 to 13.6 cGy for Cobalt 60. All 16 patients subsequently delivered full-term, normal infants. Following delivery, all of the patients had further staging procedures; eight received additional treatment. Subsequently, the disease relapsed in four patients; two eventually died of Hodgkin's disease. The 10-year determinant and overall survival rates were 83% and 71%, respectively. Currently, all offspring are physically and mentally normal, and none has developed a malignancy. Radiotherapy is an appropriate initial treatment for supradiaphragmatic presentations of Hodgkin's disease during the second and third trimesters of pregnancy, provided special attention is paid to treatment and shielding techniques. The outcome for women treated with irradiation for clinical stage I and II Hodgkin's disease during pregnancy has not been shown to be adversely affected by pregnancy, and after the first 8 weeks of gestation, the risk to the fetus appears to be minimal.