Objective: To investigate the effect of platelet membrane glycoprotein(GP) Ⅰa gene polymorphism in the pathogenesis of unstable angina pectoris (UAP) in Chinese people. Methods: Collagen type Ⅰ-induced platelet aggregation was measured in 33 healthy subjects in vitro. Plasma level of α-granule membrane protein (GMP-140) was measured in both the above 33 healthy subjects during fasting and 35 patients with recent onset effort anina during rest onset within 24 h after hospitalization. Furthermore, the platelet membrane GP Ⅰa gene 807C/T polymorphism was checked in all subjects with polymerase chain reaction-sequence specific primers(PCR-SSP) technique. Results: The lag time before 30% platelet aggregation was significantly longer in healthy subjects with CC genotype than with TC genotype (P<0.01). However, there was no significant difference in the maximal platelet aggregation between healthy subjects with the above two genotypes. Plasma level of GMP-140 was significantly higher in TC genotypic patients with recent onset effort angina than in CC genotypic patients with the same type of UAP(P<0.05) and healthy subjects (P<0.01), furthermore, there was also significant difference between the latter two groups(P<0.05). Conclusion: The rapid initiation of collagen-induced platelet aggregation may be associated with platelet membrane GP Ⅰa T (807) allele, which may play an important role in the pathogenesis of UAP. Objective: To investigate the effect of platelet membrane glycoprotein (GP) Ⅰa gene polymorphism in the pathogenesis of unstable angina pectoris (UAP) in Chinese people. Methods: Collagen type Ⅰ-induced platelet aggregation was measured in 33 healthy subjects in Plasma. of the α-granule membrane protein (GMP-140) was measured in both above the 33 healthy subjects during fasting and 35 patients with a recent onset of effort anina during rest of the hours within 24 h after transplantation. Furthermore, the platelet membrane GP Ⅰ a gene 807C / T polymorphism was checked in all subjects with polymerase chain reaction-sequence specific primers (PCR-SSP) technique. Results: The lag time before 30% platelet aggregation was significantly longer in healthy subjects with CC genotype than with TC genotype (P <0.01). However, there was no significant difference in the maximal platelet aggregation between healthy subjects with the above two genotypes. Plasma level of GMP-140 was significantly higher i n TC genotypic patients with recent onset effort angina than in CC genotypic patients with the same type of UAP (P <0.05) and healthy subjects (P <0.01), furthermore, there was also significant difference between the latter two groups Conclusion: The rapid initiation of collagen-induced platelet aggregation may be associated with platelet membrane GP Ia T (807) allele, which may play an important role in the pathogenesis of UAP.