The complement fixation test is the basic method in the diagnosis of toxoplasmosis. Due to the latter and due to the availability of the antigen it has become the “golden standard” in the diagnosis of toxoplasmosis despite the fact that this attribute is usually associated with Sabin and Feldman dye test. The results of both reactions correlate well and their standards and reproducibility are comparable. In addition to other facts the diagnostic advantage resides in the possibility of quantification of the detected levels of antibodies. The significance of the CFT for the diagnosis and evaluation of Toxoplasma infection is sufficiently known particularly in Europe.