Patients often present to the surgeon with abdominal pain, tenderness, and fever. Many exhibit progressive sepsis due to abdominal pathology. Delay in diagnosis and treatment often occurs due to the use of multiple, time-consuming, expensive diagnostic studies. We delineate the use of diagnostic laparoscopy in subsets of patients in whom confusion exists as to the cause of abdominal sepsis--i.e., females in child-bearing years, elderly patients, obese patients, immunosuppressed patients, and patients with suppression of physical findings. The methodical assessment of the entire abdominal cavity is performed utilizing manipulation of the patient's position (Trendelenburg, supine, reverse Trendelenburg, left side up, right side up) and meticulous inspection of the entire small bowel. Diagnoses included acute appendicitis, gangrenous appendicitis, perforated appendicitis with peritonitis or abscess, gangrenous cholecystitis, ischemic bowel disease, perforating carcinoma of the colon, perforating diverticulitis with abscess or peritonitis, tubo-ovarian abscess, closed-loop small-bowel obstruction, megacolon, and perforation of the colon. Laparoscopic treatment of 96% of the patients was performed successfully and a laparoscopic-assisted approach was used in the remainder. There was one mortality (cardiac) and no major morbidity. The development of a Formal Diagnostic Exploratory Laparoscopic (FDEL) approach has aided in the assessment of each of the diagnoses of sepsis in the abdominal cavity. The diagnostic and therapeutic approach laparoscopically avoids extensive preoperative studies, avoids delay in operative intervention, and appears to minimize morbidity and shorten the postoperative recovery interval.