The authors deal with articular needle biopsy with regard to the extension of knowledge and research of the articular environment. Articular biopsy is indicated in diseases associated with an articular exudate. It is made most frequently on the knee joint. In some diseases the histological picture of the articular lining is typical for the diagnosis, in some it is at least characteristic. In some instances an unequivocal interpretation of the histological finding is rather dubious from the diagnostic aspect. Needle biopsy of the joint is confronted with other findings and the clinical picture. Articular needle biopsy can be used for detection of therapeutic preparations administered systemically and in particular by the intraarticular route. Articular needle biopsy extends moreover the criteria used to evaluate the therapeutic effect.