The present study describes a case of a 60-year-old Japanese man who was histologically diagnosed with lung adenocarcinoma harboring L858R mutation of epidermal growth factor receptor. He was successfully treated with gefitinib, but eventually developed leptomeningeal carcinomatosis. He underwent ventriculoperitoneal shunting for hydrocephalus and received erlotinib in place of gefitinib with concurrent whole brain radiotherapy; this resulted in dramatic improvement in his symptoms and performance status from four to one and he survived for as long as 13.6 months after the initiation of erlotinib therapy. This multidisciplinary approach may be particularly useful in terms of increasing survival and improving quality of life.