Background: Many patients with advanced cancer are unaware of their limited prognosis, however little is known about the change in awareness during the last year of their lives. Aim: To investigate changes in the perception of prognosis in the last year of life of patients with advanced cancer and its associated factors. Design: Prospective, longitudinal, multicentre, observational study in patients with advanced cancer (eQuiPe). Patients completed 3-monthly follow-up questionnaires until death. Setting/participants: Adult patients diagnosed with advanced cancer were recruited by their treating physician or self-enrolled in one of the forty Dutch hospitals. Only deceased patients with available prognostic data were included for analysis ( n = 801). Results: Perception of prognosis changes in the last year of life with an increase in the percentage of patients who are aware of their limited prognosis (from 15% to 40%). Especially in the last 6 months of life, most of the changes were towards a more realistic perception of prognosis. Patients who did not want to know their prognosis remained relatively stable in their wish not to know (range: 14%–18%). Time to death was associated with having a perception of prognosis of < 1 year, >1 year or not knowing the prognosis, but was not associated with not wanting to know the prognosis. Conclusion: Becoming aware of their limited prognosis may make patients with advanced cancer more receptive to start end-of-life discussions. Although some patients prefer not to know their prognosis, it remains important to respectfully explore their preferences and wishes for end-of-life care.