Bone marrow aspirates from 13 patients with non-Hodgkin's lymphoma of B- and T-lineage were drawn during staging procedures and examined by a combined technique involving immune selection and gene rearrangement analysis with DNA probes specific for the heavy-chain immunoglobulin gene (JH) or T cell receptor gene (T beta and T gamma). Morphologic examination of bone marrow biopsies revealed involvement by lymphoma in one case and suspicious accumulation of blasts in another. Southern blot analysis of the samples showed the presence of a rearranged clonal band in two samples, including the morphologically involved marrow. Clonal rearrangements were not detected in the suspected marrow. Bone marrow relapses were not observed in any of these patients after a median follow-up of 20 months. Antigen receptor rearrangements are tumor-specific markers which may increase the sensitivity and the specificity of morphologic examination, and may be useful in the proper staging and follow-up of lymphoma patients.