A study of 60 patients with oro-facial granulomatosis has been conducted and the clinical presentation of this disorder defined. It encompasses the previously recognised clinical entities of Melkersson-Rosenthal syndrome and cheilitis granulomatosa. The pathological features of the disease are lymphoedema and the presence of multiple non-caseating giant cell granulomata. These granulomata are histologically indistinguishable from those found in both gastrointestinal Crohn's disease and systemic sarcoidosis. Within this series of patients, nine had evidence suggestive of gastrointestinal Crohn's disease, and in six this was confirmed. A diagnosis of sarcoidosis was made in a further two patients. The relationship of oro-facial granulomatosis to these systemic granulomatous diseases is not yet clear. Patients with oro-facial granulomatosis who have gastrointestinal symptoms should be investigated for the presence of gastrointestinal Crohn's disease. Those without symptoms should be investigated for evidence of malabsorption or serological evidence of Crohn's disease. Within the present study, the erythrocyte sedimentation rate, full blood count, corrected whole blood folate, serum albumin and calcium were the most sensitive markers of gastrointestinal involvement. Sarcoidosis should be considered in all patients with oro-facial granulomatosis. The absence of clinical signs suggestive of sarcoidosis, a normal chest radiograph and normal levels of serum angiotensin-converting enzyme makes sarcoidosis unlikely.