This is the first case report of a patient with ALK-rearranged metastatic lung adenocarcinoma who became pregnant during treatment with alectinib. A multidisciplinary team of gynecologists, neonatologists, oncologists, psychologists, and pharmacologists was set up to handle the case. According to patient's preference, the study drug was continued throughout pregnancy and the woman delivered a healthy baby girl at 35 weeks and 5 days of gestation. Fetal parameters remained normal during pregnancy. At birth, alectinib levels were 14 times higher in maternal plasma than in the fetus (259 versus 18 ng/mL). The average concentration of alectinib in the placenta was 562 ng/g. The baby was followed during her first 20 months, and no developmental anomalies were observed. After 32 months from diagnosis, the mother is well and in partial remission.