The authors subjected to histological examination a total of 38 inguinal lymph nodes from 35 patients. In 34 instances recent acquired syphilis was involved in one instance tertiary syphilis. The disease was in all patients confirmed by clinical examination, by evidence of Treponema pallidum in the luetic ulcer of the primary stage or in condylomas of the secondary stage and on serological examination by a positive BWR in blood or a positive TPI test. In three instances the histological finding in the lymph node was originally erroneously interpreted as a haemoblastoma. In two other patients the histological finding in the lymph nodes drew attention to syphilis, which before has escaped clinical diagnosis. The histological picture of syphilitic lymphadenitis in the early stage of the disease is characterized by perilymhadenitis, hyperplasia of the germ centres, proliferation of reticular cells and plasma cells and often also eosinophil cells. The finding of specific structures is rare. Vasculitis is always present. In half the patients by Warthin-Starry's method treponemas were detected.