A 36-year-old woman presented with an acute ischemic stroke and a concomitant Mycoplasma pneumoniae infection that had been proven clinically, bacteriologically, and serologically. M. pneumoniae DNA was demonstrated in cerebrospinal fluid by positive nested polymerase chain reaction, and intrathecal antibody production was also detected. Contrary to previous reports about M. pneumoniae-associated stroke, most thrombostatic abnormalities in this patient occurred after stroke onset. Although the cause of stroke remains unclear in this patient, central nervous system invasion of M. pneumoniae DNA has to be considered a possible cause in rare cases of cerebral ischemia.