A 56-year-old man who presented with backache, anemia, and renal insufficiency had an unsuccessful bone marrow biopsy from the right posterior iliac crest. A diagnosis of multiple myeloma was subsequently made on the basis of a sternal bone marrow aspiration and the presence of serum IgD/lambda monoclonal gammopathy with free lambda light chain. Since the time of iliac crest biopsy, the patient experienced persistent pain and progressive swelling at the biopsy site. Nine months later he was readmitted for a possible right gluteal abscess. A biopsy specimen disclosed an intramuscular infiltration by atypical plasma cells with positive findings for lambda light chain. This is the first reported case of needle tract seeding after bone marrow biopsy in multiple myeloma.