A comprehensive range of anti-Chlamydia test systems provides reliable serological diagnosis of infections with C. trachomatis, C. pneumoniae and C. psittaci. Serological methods are an important supplement to direct pathogen detection in the diagnosis of primary Chlamydia infections. They are, moreover, particularly useful for diagnosing persistent infections and for identifying long-term consequences of infection, such as sterility or reactive arthritis following C. trachomatis infection. The gold standard for detecting Chlamydia antibodies is microimmunofluorescence (MIF). The Anti-Chlamydia MIF provides BIOCHIP substrates of elementary bodies of C. trachomatis, C. pneumoniae and C. psittaci for parallel detection of the corresponding antibodies. The mutual lipopolysaccharide (LPS) antigen is inactivated to minimize cross reactivity. A control BIOCHIP of non-infected cells allows secure differentiation of unspecific and specific reactions. Anti-Chlamydia antibodies can also be detected using ELISA or immunoblot. The Anti-Chlamydia trachomatis ELISA utilizes native major outer membrane protein (MOMP) as the antigen for species-specific antibody detection. The Anti-Chlamydia pneumoniae ELISA is based on a cell lysate and allows genus-specific antibody detection. The immunoblot Anti-Chlamydia trachomatis EUROLINE-WB contains a unique combination of three categories of antigen: Chlamydia cross-reactive LPS, highly specific antigens from elementary bodies of C. trachomatis and highly specific recombinant MOMP antigen. This broad antigen spectrum ensures high sensitivity and specificity in the detection of antibodies against C. trachomatis. All anti-Chlamydia test procedures can be automated using specialized automation systems.