Three hundred-twenty patients with Hodgkin's disease (HD) were studied retrospectively to assess the impact of treatment on survival and the development of second malignant neoplasms (SMN). All stages of HD were considered. Treatment groups included XRT only, XRT + multiagent chemotherapy (MAC), XRT + single agent chemotherapy (SAC), and chemotherapy only (Chemo). MAC was subdivided into MOPP and non-MOPP regimens. Twenty-one patients developed 23 SMN, only two of which were acute leukemias. Survival was greatest for XRT only because of a large proportion of early stage HD in this group. SMN were seen in all treatment groups except Chemo only. The XRT + MAC group had a significantly elevated observed-to-expected ratio for SMN, but it was difficult to attribute this to either MOPP or non-MOPP due to very small numbers of patients. The actuarial risk of SMN for both MOPP and non-MOPP rises dramatically between 10 and 15 years, however, extrapolation cannot be done, again because of very small numbers. We conclude that there is an increased risk of SMN in patients treated aggressively for HD, but that the exact cause of SMN is difficult to determine.