The paper reviews results reached so far about avidity of immunoglobulins G in viral, parasitic and bacterial infectious diseases. The general introductory part begins with explanation of immunologic basis in maturation of avidity of immunoglobulins G and proceeds up to a survey of methods used for the determination of avidity. It also deals with the modes of evaluation in these methods and comments on their advantages and disadvantages. The part devoted to individual infectious diseases brings the most important information about avidity of immunoglobulins G in specific infections, especially in view of their (even potential) practical medical application, mainly in determining the phase of infection in pregnant women and in patients after transplantation. The highest attention is paid to herpes virus infections, especially the cytomegalus virus and the infections with Epstein-Barr virus, rubella and toxoplasmosis, therefore those infections, which in the given situations clearly demonstrated the contribution of avidity analysis in the solution of interpretation-difficult conditions typical for serology, such as lasting levels of immunoglobulins M and cross-reactivity of antibodies.

        Key words: avidity – immunoglobulins G – infectious diseases.