Gefitinib, a selective inhibitor of epidermal growth factor receptor tyrosine kinase is an effective agent used in the treatment of patients with advanced non-small cell lung cancer (NSCLC). Adverse drug reactions were frequently observed in the skin, gastrointestinal tract, and liver, but they were generally mild in severity and reversible. Therefore, gefitinib has been regarded as a relatively safe agent. As a serious adverse effect, however, acute lung injury has been reported. The present report describes a patient with NSCLC who developed bilateral subdural hemorrhage as a possible adverse drug reaction after gefitinib therapy. We expect that this case may provide a reference for clinicians being involved in the treatment with gefitinib.