Alectinib (Alecensa®) is a potent and highly selective anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor. Oral alectinib monotherapy is approved in the EU as first-line treatment for adults with advanced ALK-positive non-small cell lung cancer (NSCLC) and for the treatment of adults with advanced ALK-positive NSCLC previously treated with crizotinib. In the USA, alectinib is indicated for the treatment of adults with ALK-positive metastatic NSCLC. The recommended dosage for alectinib in the EU and USA is 600 mg twice daily. Well-designed phase III studies in patients with ALK-positive NSCLC showed that during up to ≈ 19 months' follow-up, progression-free survival (PFS) was significantly improved with alectinib relative to crizotinib as first-line therapy (ALEX study), and relative to chemotherapy in patients previously treated with crizotinib and platinum-doublet chemotherapy (ALUR study). Central nervous system (CNS)-related outcomes were significantly improved with alectinib in both these settings. Two phase II registrational studies (NP28673 and NP28761) in patients previously treated with crizotinib also demonstrated the efficacy of alectinib, as assessed by objective response rates (ORRs), during up to 21 months' follow-up. Overall, alectinib had a manageable tolerability profile in these settings, with most adverse events (AEs) of mild or moderate severity. Current evidence indicates that alectinib is an important treatment option for patients with advanced ALK-positive NSCLC who are previously untreated or those previously treated with crizotinib. Given its efficacy and tolerability, current guidelines include alectinib as a treatment option in these settings, with the NCCN guidelines recommending it as a preferred option for first-line therapy.