Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) show marked therapeutic efficacy in patients with non-small cell lung cancer (NSCLC) harboring the echinoderm microtubule-associated protein-like 4-ALK fusion gene. The effect on overall survival (OS) of sequential treatment with the first- and second-generation ALK-TKIs crizotinib and alectinib, respectively, has remained unknown. We have examined the clinical outcome of such sequential treatment in a retrospective analysis of patients with ALK-rearranged NSCLC.