Background: Matrix metalloproteinases (MMPs) mediate tissue injury during stroke but also neurovascular remodeling and we have shown that MMP-10 is involved in atherothrombosis. Objective: The purpose of this study was to examine the relationship between proMMP-10 and clinical outcome, assessing inflammatory and proteolytic markers, in patients with acute ischemic stroke. Methods: We prospectively studied 76 patients with ischemic stroke treated with tPA within the first 3 h from symptom onset, compared with 202 non-tPA-treated ischemic stroke patients and 83 asymptomatic subjects. Stroke severity was assessed with the National Institutes of Health Stroke Scale (NIHSS). Hemorrhagic transformation (HT) and severe brain edema were diagnosed by cranial CT. Good functional outcome was defined as a modified Rankin scale score ¿ 2 at 90 days. Serum levels of MMP-9, proMMP-10, TIMP-1, tumor necrosis factor-¿ (TNF¿), interleukin-6 and cellular fibronectin were measured at admission. The effect of TNF¿ on endothelial proMMP-10 was assessed in vitro. Results: Serum proMMP-10 concentration in ischemic stroke patients, non-treated or treated with t-PA, which was higher than age-matched healthy subjects (P < 0.0001), was independently associated with higher infarct volume, severe brain edema, neurological deterioration and poor functional outcome at 3 months (all P < 0.05), but not with HT. proMMP-10 levels were also independently and positively associated with circulating levels of TNF¿ (P < 0.0001), which induced its endothelial expression in vitro, both mRNA and protein. MMP-9, however, was only associated with HT and severe edema (all P < 0.05). Conclusions: Increased serum proMMP-10 after acute ischemic stroke, associated with TNF¿, is a new marker of brain damage and poor outcome.