Advantages and disadvantages of the peroxidase test with Treponema pallidum and the FTA-ABS test were compared. The results were veryfied through the TPI test. Sera from diseased patients suffering from various forms of syphilis, from patients with other clinical histories and from a group of (relatively) healthy persons (blood donors) were the object of the examinations. An absolute conformity of the peroxidase and FTA reaction was attained in 87.5% of cases. The authors analyzed the advantages and disadvantages of both reactions and concluded that the peroxidase reaction can be carried out only in highly specialized laboratories and therefore does not represent a dramatic back-up of the routine diagnostics of syphilis.