The involvement of matrix metalloproteinases (MMPs) in ischemic-stroke-induced infl ammatory response has recently been suggested; however, the relationship between MMPs and stroke progression has not been evaluated. We investigated the role of MMPs in neurological worsening of acute lacunar infarction. Forty- nine consecutive patients with an acute lacunar infarction (as defined by clinical and MRI criteria within 48 h after stroke onset) were evaluated. Clinical, biochemical, rheological, infl ammatory and other parameters were compared between progressive and nonprogressive groups. Among the variables, only inflammatory parameters, including MMP-9 and erythrocyte sedimentation rate, were associated with neurological worsening of acute lacunar infarction (p < 0.05). These results suggest that the infl ammatory process could play an important role in early neurological worsening of acute lacunar infarction.