Aim β-amyloid protein (β AP) may play some important role in the pathogenesis of atherosclerosis. The purpose of this study is to investigate the effect of β AP on U937 cells. Methods The β-amyloid protein was added to the media of U937 cells and the apoptosis of the cells was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and agarose gel electrophoresis, the cell cycle of U937 cells was analyzed with flow cytometry. Results TUNEL and flow cytometry showed that β-amyloid protein was able to induced apoptosis of U937 cells. Electrophoresis of genomic DNA showed internucleosomal fragments of DNA. Conclusions β-amyloid protein could induce apoptosis in U937 cells.