Résumé : Background: Elevated lactate concentration has been associated with increased mortality after out-of-hospital cardiac arrest (CA). We investigated the variables associated with high blood lactate concentrations and explored the relationship between blood lactate and neurological outcome in this setting. Methods: This was a retrospective analysis of an institutional database that included all adult (> 18 years) patients admitted to a multidisciplinary Department of Intensive Care between January 2009 and January 2013 after resuscitation from CA. Blood lactate concentrations were collected at hospital admission and 6, 12, 24 and 48 h thereafter. Neurological outcome was evaluated 3 months post-CA using the Cerebral Performance Category (CPC) score: a CPC of 3–5 was used to define a poor outcome. Results: Of the 236 patients included, 162 (69%) had a poor outcome. On admission, median lactate concentrations (5.3[2.9–9.0] vs. 2.5[1.5–5.5], p < 0.001) and cardiovascular sequential organ failure assessment (cSOFA) score (3[0–4] vs. 0[0–3], p = 0.003) were higher in patients with poor than in those with favourable outcomes. Lactate concentrations were higher in patients with poor outcomes at all time points. Lactate concentrations were similar in patients with out-of-hospital and in-hospital CA at all time points. After adjustment, high admission lactate was independently associated with a poor neurological outcome (OR 1.18, 95% CI 1.08–1.30; p < 0.001). In multivariable analysis, use of vasopressors and high PaO2 on admission, longer time to return of spontaneous circulation and altered renal function were associated with high admission lactate concentrations. Conclusions: High lactate concentrations on admission were an independent predictor of poor neurological recovery post-CA, but the time course was not related to outcome. Prolonged resuscitation, use of vasopressors, high PaO2 and altered renal function were predictors of high lactate concentrations.