Two families in which successive spouses who lived in the same house developed multiple myeloma are reported. In the first instance, a man whose first wife died of multiple myeloma remarried, and his second wife also developed myeloma. In the second family, a woman's first husband died of multiple myeloma and her second husband did too. Radiation studies of the houses and yards showed no increased radioactivity. No evidence was found for excessive exposure to chemicals or other environmental agents, for contact with other patients having similar malignancies, or for exposure to viruses or other transmissible factors. The significance of the occurrence of multiple myeloma in subsequent spouses is unknown. It is hoped that this report will stimulate research for other instances and lead to careful epidemiologic, radiologic, and virologic studies.