Abstract Objective The aim of the present study was to analyse the incidence, prevalence, mortality and cause of death data of adult SLE patients and matched controls in a full-populational, nationwide, retrospective study. Methods This non-interventional study was based on database research of the National Health Insurance Fund of Hungary. A total of 7888 patients were included in the analyses, within which two subgroups of incident patients were created: the ‘All incident SLE patients’ group consisted of all incident SLE patients (4503 patients), while the ‘Treated SLE patients’ group contained those who received relevant therapy in the first 6 months after diagnosis (2582 patients). Results The median age of the SLE population was found to be 46.5 years (women 85%). The incidence rate was 4.86 and 2.78 per 100 000 inhabitants in the ‘All incident SLE patients’ and ‘Treated SLE patients’ groups, respectively. The standardized mortality ratio was 1.63 and 2.09 in the ‘All incident SLE patients’ and ‘Treated SLE patients’ groups, respectively. Overall survival was significantly lower (P < 0.001) in both groups than in the general population, with hazard ratio = 2.17 in the ‘All incident SLE patients’ group and hazard ratio = 2.75 in the ‘Treated SLE patients’ group. There was no significant difference between SLE and control deaths regarding cerebrovascular conditions as the cause of death. Generally, cancer-related deaths were less common, while haematological cancer and infection-related deaths were more common in SLE patients. Conclusion Infections, especially sepsis, had the largest positive effect on top of the extra mortality of SLE. This highlights that SLE patients are at increased risk of infection-related death.