Summary. Bone marrow biopsies from 13 cases of lymph-node-biopsy-proven angioimmunoblastic lymphadenopathy (AILD) were studied. Eight cases (62%) showed a characteristic ‘granulomatoid’ lymphoreticular infiltrate composed of a mixture of lymphocytes, epithelioid histiocytes, immunoblasts, plasma cells and eosinophils in varying proportions. Proliferation of blood vessels, although much less prominent than that described in lymph nodes, and a marked degree of reticulin fibrosis were also noted. The pattern of involvement was mainly focal and rarely diffuse. The foci were either single or multiple, and were distributed throughout the marrow but were only rarely paratrabecular. The associated haematopoietic marrow findings were nonspecific regardless of degree of bone marrow involvement. The histopathology of involved bone marrows in angioimmunoblastic lymphadenopathy is such that in some cases it should strongly suggest the diagnosis even in the absence of a prior definitive lymph node biopsy. Differentiating features from other disorders that might be confused with AILD are discussed. Survival rate was adversely affected by bone marrow involvement.