Aim:The role of platelet-derived microparticles (PDMPs) in the crosstalk between coagulopathy and inflammation in critically ill patients remains unclear. The aim of this cohort observational study was to investigate the associations between the PDMP levels and hospital mortality or disseminated intravascular coagulopathy (DIC). Methods: This study included 119 patients who were admitted to the ICU. The PDMP levels were measured using an enzyme-linked immunosorbent assay three times a week, for a total of 372 samples. We calculated the maximum (max) PDMP value, max PDMP/platelet (PDMP/Plts) ratio (converted to the PDMP levels per 10 4 platelets) and nadir platelet count during the ICU stay. Baseline patient data and scores, including the Japanese Association for Acute Medicine (JAAM) DIC score, were collected, and potential predictors were analyzed for possible associations with hospital mortality. Results: The max PDMP/Plts ratio was significantly different comparing the survivors (n 98: median, 2.54) and non-survivors (n 21: median 17.59; p 0.001). There was a weak but statistically significant negative correlation between the max PDMP level and nadir platelet count (r 0.332, p 0.001). The max PDMP level and max PDMP/Plts ratio were higher in the DIC group (81.48 and 9.27, respectively) than in the non-DIC group (34.88 and 2.35, p 0.001 and p 0.001, respectively). The max PDMP/Plts ratio was the only variable found to be independently associated with hospital mortality according to a multivariate logistic regression analysis. Conclusions: PDMPs are involved in the development of DIC but are not related to hospital mortality. There is a good association between the PDMP/Plts ratio and hospital mortality and/or DIC in critically ill patients.