Background: Torsion of appendices epiplocae leads to an ischemic infarct of surrounding adipose tissue, causing a syndrome, called "primary epiploic appendagitis" characterized by acute abdominal pain that can simulate a surgical clinical picture. Aim: To describe the clinical picture, ultrasonographic and computed tomographic features of primary epiploic appendagitis. Material and methods: A report of patients with acute abdominal pain whose diagnosis was a primary epiploic appendagitis, diagnosed and treated in a period of 48 months. Results: fifty five patients (45 males) aged 16 to 76 years old are reported. Their clinical presentation was acute abdominal pain in the left abdominal quadrant in 48, pain in the right lower quadrant in 4 and epigastric pain in two. Two had mild fever and 12 had nausea. Ten perform physical activities prior to the onset of pain. Imaging examinations showed a 1.5 to 5 cm diameter, uncompressible small mass of adipose origin, located anteriorly and anterolaterally, between the colon and the abdominal wall. There were inflammatory phenomena surrounding the lesion and thickening of the neighboring parietal peritoneum. In all cases, the mass gradually subsided with medical treatment. Conclusions: Primary epiploic appendagitis is a relatively frequent cause of spontaneously resolving abdominal pain. It is diagnosed by ultrasound or CT scanning. (Rev Méd Chile 2000; 128: 601-7).