Pericapillary fibrin deposition is thought to contribute to the pathogenesis of venous ulceration. To our knowledge, however, there is no previous evidence that pericapillary fibrin is deposited in the tissue adjacent to venous ulcers. We prospectively studied patients with ulcers of the lower extremities for the presence of dermal pericapillary fibrin in the skin adjacent tot he ulcers. On direct immunofluorescence, pericapillary fibrin was found in 14 (93%) of the 15 patients with venous ulceration but in only one (7%) of the 14 subjects with ulcers due to other causes. We also confirmed the presence of dermal pericapillary fibrin in legs with venous disease without ulcerations. We conclude that the pericapillary fibrin is easily demonstrable in the dermis adjacent to venous ulcers. In the evaluation of ulcers due to uncertain causes, the presence of dermal pericapillary fibrin may provide additional diagnostic help.