The various forms of arthritis associated with a gonococcus infection are pathogenetically and clinically differentiated. Whereas an infectious systemic process with different clinical symptoms is said to be underlying the arthritis-dermatitis syndrome as well as the septic GO-arthritis, the third form is para-infectious reactive arthritis. It is often difficult to diagnose an infectious GO-arthritis, as direct evidence of the virus found in joint and blood is rarely positive, so that the diagnosis can be affirmed or negated on the basis of clinical facts of the reaction of arthritis after an appropriate antibiotic therapy. Differential diagnostic considerations may help to find the correct diagnosis in view of an acute urethritis arthritis.