Right lower quadrant pain is a very common symptom in everyday clinical practice, and of variable etiology. In patients arriving in the emergency room with sudden-onset right lower quadrant pain, the commonest cause is acute appendicitis. Primary epiploic appendagitis, a rare entity, with a clinical presentation similar to other causes of acute abdomen, and one that subsides spontaneously, can constitute a problem in differential diagnosis, because it is a condition best treated conservatively. The exact diagnosis is a prerequisite for conservative treatment. We present the case of a 62 year old woman with primary epiploic appendagitis of the ascending colon that presented as acute abdomen, who underwent an exploratory laparotomy with the preoperative diagnosis of acute appendicitis.