Progressive motor deficits are relatively common in acute pontine infarction and frequently associated with increased functional disability. However, the factors that affect the progression of clinical motor weakness are largely unknown. Previous studies have suggested that pontine infarctions are caused mainly by basilar artery stenosis and penetrating artery disease. Recently, lower pons lesions in patients with acute pontine infarctions have been reported to be related to progressive motor deifcits, and ensuing that damage to the corticospinal tracts may be respon-sible for the worsening of neurological symptoms. Here, we review studies on motor weakness progression in pontine infarction and discuss the mechanisms that may underlie the neurologic worsening.