Use of Lorlatinib, a third-generation tyrosine kinase inhibitor currently indicated in the treatment of non-small-cell lung cancer (NSCLC) with ALK or ROS1 gene fusion, is formally contra-indicated during pregnancy due to teratogenic effects observed during pre-clinical studies. We report the case of a 38-year-old woman with a ROS1-positive NSCLC, successfully treated with lorlatinib as second line therapy, who became pregnant while on treatment. Due to significant disease progression 12 weeks after lorlatinib stop and the great uncertainty on the pregnancy outcome, she finally decided to interrupt the pregnancy at 22 weeks of gestation. Echography and gross infant examination did not reveal any malformation. Pregnancies occurring under this kind of new oncologic treatment is expected to happen more frequently in the future. It seems therefore important to us to report any information on the topic to increase our level of knowledge and improve decision-making.