[SUMMARY] This study aimed to clarify late adolescents’ experience with parental cancer and the support sought from medical professionals regarding living with parents who had cancer. An anonymous self-administered questionnaire survey was conducted to collect data from 570 men and women between the ages of 18 and 22 who were enrolled in a four-year university course (recovery rate of 85.0%, response rate of 95.0%). The questionnaire covered personal characteristics, experience with parental cancer, and the support sought from medical professionals regarding living with parents who had cancer. Descriptive statistics were calculated using IBM SPSS Statistics 25.0, and the contents of free-text responses were analysed using NVivo. Of the participants, 45.3% had had a close relative with a cancer diagnosis, including grandparents, and 10.4% had lived with that person. 4.4% of the participants had experience with parental cancer, more than half of them felt that they did not know what to do to support a parent who had cancer, and all of them experienced feeling alienated, lost, or alone. In addition, when participants remembered or imagined living with parents who had cancer, the most crucial element of support from medical professionals was in terms of information regarding cancer and its treatment, ways to deal with the appearance of and sudden changes in physical symptoms, and other specific methods to support parents living with cancer. Among the types of support sought from medical professionals, more than 90% of the participants indicated that they would like ‘a place where children of cancer patients can directly meet and consult with medical professionals about their worries caused by their parents’ cancer’ to better understand and solve specific problems. These results indicate that late adolescents living with parents who had cancer seek support from medical profes-sionals to obtain correct information to understand their parents’ situation and find ways to help them.