Crizotinib and alectinib are an oral, selective, small-molecule tyrosine kinase inhibitor targeting anaplastic lymphoma kinase (ALK). These two drugs are effective in patients with advanced non-small cell lung cancer with ALK/EML4 rearrangement. On the other hand, in spite of the drastic anti-tumor activity of Crizotinib as shown in the recent trials, Intestinal lung disease (ILD) was recognized as one of the serious adverse effect. However, the safety of subsequent administration of alectinib in patients with crizotinib induced ILD is uncertain. Here, we describe an EML4-ALK positive NSCLC patients who was successfully treated with alectinib after the onset of ILD induced by crizotinib.(Case presentation)A 58-year-old woman with never-smoking history referred from primary clinic with a suspicion of pneumonia. Chest CT showed diffuse consolidation on the left lower lobe, which was proved by bronchoscipic biopsy to be adenocarcinoma. Mutation analysis revealed negative EGFR mutation and positive ALK/EML4 rearrangement. Crizotinib was administered orally at a dose of 250mg twice daily. The tumor dramatically responded to crizotinib within one week and her symptom was resolved. On the 15th days from the initiation of crizotinib, she felt dyspnea and chest CT demonstrated ground-grass opacities on both lung fields. Because there were lacking of evidence of infection or other cause, she was diagnosed with ILD induced by crizotinib and prescribed prednisolone. Subsequently, pulmonary lesion ameliorated after the discontinuation of crizotinib. With improvement of her symptom, we prescribed alectinib as second-line therapy. She has kept in good condition and under control of disease without any adverse effect. Crizotinib and alectinib are an oral, selective, small-molecule tyrosine kinase inhibitor targeting anaplastic lymphoma kinase (ALK). These two drugs are effective in patients with advanced non-small cell lung cancer with ALK/EML4 rearrangement. On the other hand, in spite of the drastic anti-tumor activity of Crizotinib as shown in the recent trials, Intestinal lung disease (ILD) was recognized as one of the serious adverse effect. However, the safety of subsequent administration of alectinib in patients with crizotinib induced ILD is uncertain. Here, we describe an EML4-ALK positive NSCLC patients who was successfully treated with alectinib after the onset of ILD induced by crizotinib. (Case presentation) A 58-year-old woman with never-smoking history referred from primary clinic with a suspicion of pneumonia. Chest CT showed diffuse consolidation on the left lower lobe, which was proved by bronchoscipic biopsy to be adenocarcinoma. Mutation analysis revealed negative EGFR mutation and positive ALK/EML4 rearrangement. Crizotinib was administered orally at a dose of 250mg twice daily. The tumor dramatically responded to crizotinib within one week and her symptom was resolved. On the 15th days from the initiation of crizotinib, she felt dyspnea and chest CT demonstrated ground-grass opacities on both lung fields. Because there were lacking of evidence of infection or other cause, she was diagnosed with ILD induced by crizotinib and prescribed prednisolone. Subsequently, pulmonary lesion ameliorated after the discontinuation of crizotinib. With improvement of her symptom, we prescribed alectinib as second-line therapy. She has kept in good condition and under control of disease without any adverse effect.