Objective To investigate the effects of constant magnetic field (CMF) on proliferation, apopto-sis and nitric oxide (NO) secretion of rat bone marrow-derived endothelial progenitor cells (EPCs) intervened by C-reactive protein (CRP). Methods EPCs were isolated from rat bone marrow by density gradient centrifugation and cultured on fibronectin-coated dishes. The cells were divided into five groups, i. e., control group, CRP (12 μg/ml) group, CRP plus CMF (0.1, 0. 5, 1.0 mT) groups. Samples were collected 24 hours after incubation. Cell proliferation was measured by MTT chromatometry. Apoptosis rate was detected by flow-cytometry. NO content of culture medium was measured by nitrate reductase method. Results As compared with control group, cell prolifer-ation in CRP group reduced significantly (0. 265±0. 008 vs 0. 316±0. 011, P < 0.05), NO secretion also de-creased significantly [(22.7±4.5) μmol/L vs (37.6±3.8) μmol/L, P < 0.05], cell apoptosis rate elevated sig-nificantly [(10.8±0. 8) % vs (4.2±0.5)% ,P < 0.05]. Cell proliferation in CRP plus 0. 5 mT or 1.0 mT CMF group (0. 295±0. 009,0. 302±0. 010) were much more than those in CRP group (P<0.05), NO secretion contents [(28.3±4.9) μmol/L, (29.2±5.6) μmol/L]were also much more than those in CRP group (P < 0.05) , apopto-sis rate [(7.4±0.5)% ,(6.9±0.6)%]was significantly lower than that in CRP group (P <0.05). Conclusion CMF at intensity of 0.5 mT and 1.0 mT can antagonize the effects of CR, promote proliferation of EPCs and secretion of NO and inhibit apoptosis rate of EPCs.