Summary Whole bacteria and the supernatant broth of their forty-eight-hour cultures were injected intradermally into patients with chronic rheumatoid arthritis and into allergic and nonallergic controls. Previous findings of increased tendency of arthritic patients to react to streptococci or their products were confirmed. It was also again determined that hemolytic streptococci gave the most marked and most frequent reactions. It was found that the increased skin sensitivity was limited to streptococci. The staphylocci and gram-negative organisms did not similarly affect the skin of arthritic patients. None of the findings justified the assumption of a specific organism. A history of hay fever, asthma, urticaria or eczema profoundly affects the results of tests with the supernatants of broth cultures. The number of positive tests is directly proportional to the content of irritant, nonspecific substances. This nonspecific irritant factor renders valueless skin tests of an individual with unstandardized autogenous bacterins or other autogenous bacterial products not previously standardized by tests on control individuals.