Atypical bacteria, such as Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila, are major causes of respiratory infections. Infections can be asymptomatic, with mild symptoms or can further develop into a severe form of pneumonia requiring hospital care. Since the afore mentioned pathogens are resistant to beta-lactam antibiotics, it is of great importance for patients’ treatment that they be identified early enough as infection causes. Due to their specific cellular structure and multiplication conditions, it is difficult to separate them from the clinical samples; to be more precise, the isolation method is challenging, time-consuming, and has a low sensitivity rate. Serologic tests are also lengthy, for in order to confirm the acute infection, steam sera are needed. Consequently, the diagnostics are mostly carried out with molecular tests such as multiplex PCR test which enables the simultaneous detection of infections with whichever atypical bacterium. The objective of this thesis is to evaluate more recent diagnostic multiplex PCR tests by TIB MolBiol, Seegene, Fast Track and AusDiagnostic. Our predictions were that they would have a higher sensitivity detection than the test that is currently in use, in addition to being easier to perform. The results have shown that not all tests are more sensitive than the Argene test and confirmed that they really are more user-friendly.