Introduction Platelet refractoriness (PR) is a frequent complication in multitransfused patients, due to non-immune and immune factors. Brazilian population has a distinct ethnical background, and few data are available of PR. This study aimed to evaluate clinical and laboratory features of haematological patients with suspected PR from a Brazilian regional reference centre. Material and methods Haematological patients (pts) with clinical suspected PR were included from February 2007 to 2014. Platelet Abs and anti-HLAAbs identification, HPA and HLA genotyping performed. Clinical information obtained from medical records.Results Total of 624 patients were evaluated, and incidence of PR observed was 7%. Among 93 patients with clinical suspicion of PR, 45Á2% had PR confirmed. HLA antibodies were present in 80Á9% among PRpts in 60Á6% of non-PRpts (no significant difference). Immune PR(IPR) isolated was identified in 11Á9% of the PR patients and in association with non-immune causes in 69Á05%. Isolated nonimmune PR (NIPR) was present in 19Á1% of cases. IPR patients had higher HPA-Abs frequency compared to I+NIPR group (P = 0Á026), with similar HLA Ab frequency (100%) in both groups.Discussion Incidence of 7% found is within the range(75%-34%) described by literature. Non-immune factors such as fever and antibiotics were main cause found present in more than 80% of cases and immune causes were mainly associated with HLA antibodies as expected. Interestingly, no anti-HPA-1a antibodies were identified, the most common specificity described in other populations. However, anti-HPA-5b and anti-HPA-3b antibodies were detected. This finding suggests that possible unidentified factors would lead to a distinct pattern of platelet alloimmunization as previously described for fetal-neonatal alloimmune thrombocytopenic purpura in Brazil.