A case of relapsing polychondritis (RP) with severe respiratory tract involvement is reported. The patient's subsequent course included ulcerative colitis and further collapse of nasal cartilage. Antibody titers to cartilage were serially determined by indirect immunofluorescence and levels of circulating immune complexes (CIC) by 3 different techniques. The exacerbations of RP appeared to be reflected by the elevation of anticartilage antibody titers and some elevation in the levels of CIC as detected by the polyethylene glycol method.