Tamoxifen has been shown to induce apoptosis in multiple myeloma cell lines and primary myeloma cells. Daily tamoxifen was given to 12 consecutive multiple myeloma patients who either relapsed following autologous stem cell transplantation (11) or had progressive disease on conventional chemotherapy (1). Methotrexate was also given biweekly to enhance the antiangiogenetic effect. Two patients achieved complete remission lasting 8 and 18 months. Two additional patients had stable disease (SD) for 7 and 11 months. All responders were men and the earliest signs of response were seen after approximately 6-8 weeks of treatment. The regimen was very well tolerated. Speculations about a possible mechanism of action of tamoxifen in multiple myeloma are discussed.