Background: Lp-PLA2 is a novel biomarker in cardiovascular diseases due to its ability to predict first-ever and recurrent stroke. Little information is known regarding its influence on early outcome after stroke., Objectives: We aimed to investigate Lp-PLA2 in t-PA-treated stroke patients and to study its relationship with early outcome., Methods: Lp-PLA2 mass and activity were measured in 135 healthy controls and also in stroke patients treated with t-PA at baseline (n=99) and serially thereafter (n=34) by means of the PLAC test at an automated Olympus analyzer and by a colorimetric activity method (diaDexus). NIHSS scores and TCD recordings were also obtained serially. Outcome was defined according to early neurological status, the presence of arterial recanalization and functional outcome at third month., Results: Lp-PLA2 mass was increased as compared to controls, whereas Lp-PLA2 activity was significantly decreased at baseline as compared with controls and with 1 and 24 h determinations. Lp-PLA2 mass and activity were not related with early (48 h) neurological status. Regarding recanalization, higher mass and activity were found among patients who did not achieve complete recanalization by the end of t-PA treatment (p=0.029 for mass, p=0.044 for activity). Lp-PLA2 mass and the existence of a proximal occlusion at baseline were the most powerful predictors for persistent occlusions (OR for proximal occlusion 6.8. p=0.036, OR for Lp-PLA2 mass 7.2 per standard deviation increase, p=0.008)., Conclusions: Significant changes in Lp-PLA2 concentrations occur early after stroke onset. Lp-PLA2 mass may add relevant information regarding early arterial recanalization in intravenous t-PA-treated stroke patients., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)