Appendicular abscess occurred in 14.2% of patients presenting acute appendicitis. Management of these patients remains controversial, ranging from an emergency appendectomy to a nonoperative treatment. On board French nuclear submarines, the usual treatment for all cases of appendiceal masses, including both appendicitis and appendiceal abscess, is an appendectomy. In the past 5 years, the introduction of ultrasonography (US) on board has enabled the diagnosis of appendiceal abscess with a high rate of accuracy, and the latest studies show that nonoperative treatment is an alternative approach. This nonsurgical treatment, based on intravenous administration of antibiotics, is successful in about 93% of the patients. Failure of nonsurgical treatment is a reliable indication of percutaneous drainage. The proportion of adult patients who need percutaneous drainage of abscesses is about 27%. A successful primary nonoperative treatment may or may not be followed by interval appendectomy at the conclusion of the patrol. Nonsurgical treatment is associated with a significantly lower morbidity than surgery. Considering that the on-board surgical facility is limited, nonsurgical treatment appears to be the best approach for treating a sailor with an appendiceal abscess during a submarine patrol mission.