Objecfive To investigate the effects of treatment for cerebrovascular disorder patients with heparin and low molecular weight heparin(LMWH) on serum PAPP-A concentrations and provide the basis for evaluating the clinical significance of PAPP-A in the following study.Methods Forty cases with cerebrovascular disease from Qilu Hospital from November 2009 to May 2010 were collected in this study.Blood samples were taken before and after drug administration.All cases were divided into four groups according to situation of medication.Group A consisted of 10 patients who received subcutaneous LMWH anticoagulation therapy, and blood samples were collected before LMWH injection, three hours after subcutaneous LMWH anticoagulation therapy in the first day, the second day and the seventh day and 24 hours after the last injection. Group B consisted of 10 patients who did not receive LMWH therapy, and blood samples were collected immediately after admission, the first day, the second day and the seventh day after admission. Group C consisted of 10 patients with percutaneous carotid intervention who received intravenous heparin at the beginning of stenting, and blood samples were collected from the arterial sheath just before angiography and heparin administration, and at 3, 5, 15, 40 and 100 min after heparin administration. Group D consisted of 10 patients who received carotid angiography but LMWH-free therapy,and blood samples were collected from the arterial sheath just before and after angiography. Serum PAPP-A concentrations were analyzed by ELISA to evaluate the differences of intra-groups and differences at different time points of inter-groups. Results In group A, PAPP-A concentrations were time dependent and elevated gradually from 12. 36 (9. 90-14. 32) mIU/L before LMWH injection to 21.80 (23.50-19.73) mIU/L at the seventh day after injection (M=38. 72, P < 0.01 ). In group C, there was a rapid increase of PAPP-A concentration from 12. 86 ( 9. 67-14. 05 ) mIU/L to 51.56 ( 44. 20-66. 00 ) mIU/L within 5 min after intravenous heparin injection (M=46. 06, P <0. 01 ). The PAPP-A concentration of one week after LMWH administration in group A was 21.80 (23.50-19.73) mIU/L, significantly higher than that in group B [11.81 (9. 21-12. 89) mIU/L] (U<0. O01, P<0.01). The PAPP-A concentration at 15 min after heparin administration in group C was 43.70 (37.70-54. 30) mIU/L, significantly higher than that after angiography in group D [14. 18 (11.25-15. 86) mIU/L] ( U<0. 001, P <0. 01 ). The peak level of blood PAPP-A after subcutaneous LMWH injection was significantly lower than that after intravenous heparin injection. The concentrations in group A and C were 21.80 ( 23.50-19. 73 ) and 51.56 (44. 20-66. 00) mIU/L respectively, and had a significant difference ( U=0. 999, P < 0. 01 ) . Conclusions Both intravenous heparin and subcutaneous LMWH administration induce an increase in serum PAPP-A concentration. The effect of drug should be considered when PAPP-A is selected as an evaluation indicator.