Aims and objectives To describe registered nurses' work with sick leave questions by telephone. BackgroundIn Sweden, when a sick person needs to request a sickness certification, it is common to contact the primary healthcare centre. The main access to primary health care is by telephone, with a registered nurse answering the care seeker's questions, triaging and helping care seekers to the right level of care. Registered nurses' work with sick leave questions has not been studied, except for two qualitative interview studies. DesignA descriptive cross-sectional study. MethodsA questionnaire with 120 questions was distributed to 185 registered nurses in one county in central Sweden. Descriptive statistics were used for analysis. ResultsResponse rate was 62% (n=114). Registered nurses (n=105) in this study talked weekly to persons on, or at risk, for sick leave. A large part (n=78) felt they had a role in the care of persons on sick leave, consisting of booking appointments as well as acting as a pilot, advisor, caretaker and coordinator. For 74 of 114 registered nurses, it was problematic to handle the phone calls weekly. Measures were often' booking appointments with physicians (n=67) and seldom' providing information on social insurance rules (never' n=51). The registered nurses expressed a great need for more education. ConclusionRegistered nurses in this study reported having a role in the care of persons on sick leave when handling sick leave questions by telephone. The telephone calls were problematic to handle, and the registered nurses expressed a great need for education and training in social insurance medicine. Relevance to clinical practiceThere is a need to educate and train registered nurses in social insurance medicine to provide high-quality nursing for patients on or at risk for sick leave.