Syphilis or Lue is a venereal infectious disease, whose etiological agent is Treponema Pallidum. The infection is spread through contact on skin. Treponema antigenic structure is not completely known, but three different kinds of antigens can be distinguished: lipoid antigen, proteic antigen and polysaccharide antigen. The diagnosis can be directly done on Treponema Pallidum (TPHA method) or indirectly (serum diagnosis), highlighting specific antibodies anti- Treponema (reagines). This kit is based on anti-antigen lipoid antibody identifying by flocculation reaction (V.D.R.L.). The lipoid antigen is represented by an alcoholic extract of ox heart with addition of cholesterol and lecithin. This exctract is called Cardiolipin. Bound with carbon molecules (RPR method), cardiolipin in the presence of specific antibodies in the sample forms some aggregates meaning positivity.