The study evaluated the course and outcome of erythema migrans in patients receiving tumour necrosis factor-alpha (TNF-α) inhibitors. Among 4157 adults diagnosed with erythema migrans in the period 2009-2018, 16 (2.6%) patients were receiving TNF-α inhibitors (adalimumab, infliximab, etarnecept, golimumab), often in combination with other immunosuppressants, for rheumatic (13 patients) or inflammatory bowel (three patients) disease. Findings in this group were compared with those in 32 sex- and age-matched immunocompetent patients diagnosed with erythema migrans in the same years. In comparison with the control group, the immunocompromised patients had a shorter incubation period (7 vs. 14 days; 