Afatinib is a newly approved second-generation epidermal growth factor receptor-tyrosine kinase inhibito r(EGFR-TKI). Afatinib has been shown to prolongthe overall survival of patients with non-small cell lungcancer (NSCLC) with EGFR mutations compared with the standard chemotherapy. However, Grade 3 or 4 toxicities, includingdiarrhea, rash, paronychia, and stomatitis, have been observed more frequently in patients treated with afatinib than in those treated with first-generation EGFR-TKIs. Accordingly, our institution developed an afatinib clinical pathway (the afatinib pathway), which was designed by certified nurses, medical physicians, and certified pharmacists, with the goal of reducing the severity of diarrhea and rash that occur most frequently duringthe 28-day introductory period of afatinib treatment. Between May and October 2014, afatinib was administered accordingto the afatinib pathway to 14 patients with NSCLC and EGFR mutations. Of these patients, only one (7.1%) experienced Grade 3 diarrhea. No other patient experienced Grade 3 or 4 toxicity. The afatinib pathway was effective in reducingthe severities of the diarrhea and rash duringthe 28-day introductory period of the afatinib treatment. Our implementation of the afatinib pathway could be considered the Japanese style of collaborative drugtherapy management (J-CDTM).