PURPOSE: Sparse data exist on delirium in VA-ECMO. We aim to describe the characteristics, risk factors, and outcomes of delirium in VA-ECMO. METHODS: We retrospectively reviewed adults's electronic medical records on VA-ECMO in our ECMO registry in 2016-2022. Delirium was assessed by the Confusion Assessment Method for the intensive care unit when patients scored -3 or above on the Richmond Agitation-Sedation Scale. The primary outcomes were delirium prevalence and the proportion of delirium-present days while on VA-ECMO support. Multivariable logistic regression was used to evaluate delirium risk factors. RESULTS: Of 208 patients (median [interquartile range] age: 53 [40-62]), 138 (66.3%) had delirium during ECMO. Delirium occurred on day 2.5 [1.0-7.0] of ECMO and was detected in 42% [20%-66%] of ECMO days. There were no differences in acute brain injury (24% vs 33%, CONCLUSIONS: Delirium was present in 66.3% of VA-ECMO patients and was detected early during ECMO. Modifiable risk factors included multiple sedative agents and early hypercapnia. Delirium did not increase risk for mortality.