AIM: Survivors after cardiac arrest (CA) exhibits a systemic inflammatory response as part of post-cardiac arrest syndrome (PCAS). We investigated the association between systemic inflammation and severity of PCAS and whether level of targeted temperature management (TTM) modifies level of the inflammatory response. METHODS: We studied 169 patients included at a single center in the TTM-trial, randomly assigned to TTM at 33 °C or 36 °C for 24 h. Plasma samples were analyzed for inflammatory markers including interleukin (IL) IL-1β,IL-4,IL-6,IL-10, tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and procalcitonin (PCT) at randomization and 24, 48 and 72 h after CA. Severity of PCAS was assessed by Sequential Organ Failure Assessment (SOFA) score. RESULTS: Plasma levels of both IL-6 and IL-10 determined at randomization correlated with severity of PCAS at day 2 (r=0.36 and r=0.27, p<0.001) and day 3 (r=0.32 and r=0.22, p<0.001). IL-6 at randomization was an independent predictor of severity of PCAS at day 2 (p=0.003) and day 3 (p<0.0001) and was a significantly stronger predictor of severity of PCAS at day 3 compared to CRP (p=0.04) and PCT (p=0.03). Level of TTM did not modify level of the inflammatory markers IL-1β, IL-6, TNF-α, IL-4, IL-10, CRP and PCT, (p=NS for each inflammatory marker). CONCLUSIONS: Level of inflammatory response was associated with severity of PCAS with IL-6 being consistently and more strongly associated with severity of PCAS than the inflammatory markers CRP and PCT. The systemic inflammatory response after CA was not modified by TTM at 33 °C or 36 °C.