BACKGROUND: In western countries, patient participation is requested in policies on mental health services. Participation is built on ideas of democracy and individual responsibility. Mental illness has, however, been characterized by its irrational features. AIM: To investigate mental health service users' and providers' views on patient participation during episodes of mental illness. METHODS: Qualitative interview study with 20 users and 25 staff from a mental health hospital in central Norway. RESULTS: Both users and professionals saw poor illness phases as an obstacle to patient participation. Lack of insight, lack of verbal ability and difficulty cooperating made participation difficult. During such phases, patient participation was redefined. There was a shift in responsibility where professionals took charge through strategies of providing information, motivating patients and reducing choices. Respect and dignity were maintained and not redefined. CONCLUSIONS: In poor phases of mental illness, patient participation was redefined and weighed against what was perceived to be the patient's best interest.