The general aim was to describe the frequency of and the reasons for locked doors at wards within Swedish psychiatric care. A questionnaire was answered by 193 ward managers. The findings demonstrated that 73% (n = 193) of the wards were locked on the day of investigation. Wards were sometimes locked in the absence of committed patients and sometimes open in the presence of committed patients. Wards were more often locked if at least one committed patient was present. Fewer wards for children and adolescents, than for adults and old people, were locked. More wards in the areas of Sweden's three largest cities, than in the rest of the country, were locked. Fourteen categories of reasons for locking wards were generated by a content analysis of answers to an open-ended question. Most answers were categorized as: prevent patients from escaping, legislation, provide patients and others with safety and security, prevent import and unwelcome visits, and staff's need of control. Staff working in psychiatric care ought to reflect upon and articulate reasons for, and decisions about, locking or opening entrance doors, with the limitation of patients' freedom in mind.