A 21-year-old man had sudden-onset right hemiplegia and aphasia with respiratory infection. A chest X-ray disclosed consolidation in both lungs and magnetic resonance imaging showed an embolism in the left middle cerebral artery. A pelvic computed tomography scan revealed deep venous thrombus in both femoral veins. Patent foramen ovale was detected by transesophageal echocardiogram. Antibodies to M. pneumoniae were highly elevated, and hypercoagulability was subsequently detected. This case suggests that the possible pathogenic mechanism for M. pneumoniae infection-related stroke might be paradoxical brain embolism with deep venous thrombus as a consequence of the hypercoagulability related to this infection.