Antigen was injected into the gingiva and tested for its ability to induce a flare of a chronic arthritis. Joint inflammation was established by a local injection of 100 μg methylated bovine serum albumin (mBSA) in the right knee joint of immune mice. About 4 wk later, 0·5‐1 mg mBSA was injected into the gingiva. It was found that this antigenic challenge induced a flare of the arthritis as measured with the99mTechnetium (99mmTc) uptake method. Light microscopic examination of the knee joints revealed an increase of inflammatory cells in the synovial tissue and the joint space. The results indicate that, under certain experimental conditions, antigenic material administered to the gingiva can influence an inflammation elsewhere in the b