Introduction: The sticky platelet syndrome (SPS) seems to be a common cause of thrombosis, although no molecular substrate to explain platelet hyperaggregability has been found. Objective: To analyze an association between the SPS phenotype and the platelet glycoprotein (GP) IIIa PL^A1/A2 (human platelet antigen [HPA]-1a/b) gene polymorphism. Methods: Along an 18-month period, Mexican mestizo thrombophilic patients were prospectively accrued. The SPS phenotype was assessed by aggregometry, whereas a tetra-primer amplification refractory mutation system (ARMS) polymerase chain reaction analysis was used to detect the PLA1 and PLA2 alleles. Results: A total of 95 individuals with SPS and 127 healthy donors were studied; in 11 of the donors and 16 of the patients with SPS the A2 allele of the GP IIb/IIIA was found, yielding a weak and nonsignificant association (odds ratio 2.14, 95% CI 0.94-4.85). Conclusion: In Mexican mestizo patients, the platelet GP IIIa PL^A1/A2 gene polymorphism does not lead to the SPS phenotype.