A new rapid technique for detection of serum treponemal antibodies is described which is based on an enzyme-linked immunoassay using nitrocellulose as solid phase. With this technique antigen-antibody binding is accelerated by the filtration of the antibody solution through the antigen-coated nitrocellulose filter instead of its remaining over the solid phase for incubation. Test results are available in less than 15 min. Serum specimens from 255 syphilitics and 829 non-infected subjects were investigated. The sensitivity and specificity of the Treponema pallidum enzyme-linked immunofiltration assay were comparable to those of the Treponema pallidum haemagglutination assay and the fluorescent treponemal antibody absorption test.