The aim of this study was to investigate the antimyeloma effect of recombinant human endostatin (rhES) in vitro and its mechanism. The inhibitory effect of rhES on proliferation of multiple myeloma cell line CZ-1 was assayed by trypan blue dye exclusion and MTT method, the apoptosis-inducing effect of rhES on CZ-1 cells was detected by transmission electron microscopy and flow cytometry with Annexin V-FITC and PI double staining. The effects of rhES on primary bone marrow cells of patients with MM and healthy adults were also investigated. The results showed that the rhES at concentrations of 50, 100 and 200 microg/ml for 72 hours could inhibit the proliferation of CZ-1 cells, and their inhibition rates were 10.5%, 17.9% and 23.5% respectively. The inhibitory effect of rhES on CZ-1 cells was time- and dose-dependent. 50 - 200 microg/ml rhES could also inhibit the growth of primary bone marrow cells of multiple myeloma patients, while 0 - 400 microg/ml rhES had no inhibitory effect on primary bone marrow cell of healthy adults. 100 microg/ml rhES could induce CZ-1 cell apoptosis after administration for 72 hours. The typical manifestation of apoptotic cells could be observed by transmission electron microscopy. The apoptotic rate of CZ-1 cells was 21.37%. It is concluded that rhES can inhibit the proliferation of multiple myeloma cells by inducing apoptosis. Whether rhES may be a candidate medicine for the treatment of multiple myeloma is to be further studied.