Knowledge of test procedures is essential for an optimal approach in rheumatological and immunological diagnostics as well as for acorrect interpretation of the findings. In practice, they are abasis for the independent provision of diagnostic laboratory services. For scientific questions they have become indispensable tools in many areas. This article gives an overview on the most frequently used and important test methods in acomprehensive form. The advantages and performance of the different methods are addressed and the limitations and possible sources or error are discussed. Quality control increasingly plays a decisive role in the diagnostic and scientific practice, with the legal regulations applying to all test procedures in laboratory diagnostics. For the discipline of rheumatology, the rheumatological and immunological diagnostics are of particular importance as the majority of the known disease-specific markers are detectable by means of these procedures. At the same time, immunological laboratory diagnostics are a highly interesting field of activity which are expected to have a strong impact on the future developments in rheumatology.