The authors report their experience in relation to a series of 12 cases of hematoma of the rectus abdominis (ER) observed over the course of 13 years at the 2nd Division of General Surgery at Vicenza Hospital: 7 were spontaneous, 2 post-traumatic, 1 occurred during anti-coagulant treatment, 1 in a patient with altered coagulation levels due to liver cirrhosis, and 1 was post-operative. Clinical symptoms were sub-acute in 8 cases and were characterised by abdominal pain in all cases, the appearance of an abdominal mass in 4 cases and by ecchymosis in 3 cases. Symptoms were acute in 4 cases with signs of impaired general conditions and anemia. Echography made a decisive contribution to the diagnosis in this pathology and, based on the author's experience, when it was used it prevented the use of surgery. Computerised axial tomography, although it contributed a few precise findings to the diagnosis of ER, was rarely useful. Eight patients were operated: 2 due to collapse and anemia, 4 due to failure to identify the disease, 1 due to persistence of the parietal mass, and 1 due to infection of the hematoma. In the 4 cases which were not operated, the course of the disease was more favourable. The sole death was an elderly cardiopathic patient due to postoperative complications following general surgery. The most suitable therapeutic approach, in those cases where an accurate diagnosis of ER has been made, is to refrain from any form of treatment and to monitor symptoms until they resolve, which will occur spontaneously after 20-30 days.(ABSTRACT TRUNCATED AT 250 WORDS)