Background: Different polymerase chain reaction (PCR) techniques for human platelet antigens (HPA) genotyping have been implemented, in order to diagnose the clinical syndromes of patients with thrombocytopaenia and provide effective HPA-matched platelet donors. Objectives: The aim of this study is to develop an in-house multiplex PCR for HPA-1 to -7 and -15 genotyping in the Thai population. Methods: One hundred DNA samples of known HPA genotyping by the PCR with sequence-specific primers (PCR-SSP), as previously described, were tested with the multiplex PCR. Additionally, 300 DNA samples of group O donors were tested for HPA-1 to -7 and -15 genotyping using multiplex PCR. Results: The comparison of HPA-1 to -7 and -15 genotype results between multiplex PCR and PCR-SSP technique was in 100% concordance. Interestingly, HPA-2b2b genotype was found in two samples; however, other low-incidence genotypes such as HPA-1b1b, HPA-5b5b, HPA-6b6b and HPA-7b7b were not found in this study. Moreover, 30 samples were randomly tested twice for HPA genotyping using the multiplex PCR and demonstrated reproducible results. Conclusions: This study shows that the in-house multiplex PCR is simple, cost-effective and suitable for HPA genotyping for routine laboratories in other developing countries. Nevertheless, a large-scale evaluation of this technique through multicentre analysis is suggested. © 2012 The Authors. Transfusion Medicine © 2012 British Blood Transfusion Society.