Richter's hernia is a deceptive entity with a high mortality which can be reduced by accurate diagnosis and early operation. Richter's hernia, or partial enterocele, is a protrusion of the antimesenteric surface of bowel wall into any abdominal hernia. It is deceptive because strangulation may occur early; frequently, in the absence of obstructive symptoms. The high mortality associated with this lesion has resulted from misdiagnosis and delayed operation. Review of Material A recent review of acute mechanical intestinal obstruction at this hospital indicated that 13% of the cases of incarcerated or strangulated hernia were of the Richter's type. The conflicting physical and roentgen findings and the mortality of 33% in this group stimulated further study. We have had experience with 20 patients with Richter's hernia. The average age was 70 years; the youngest patient was 8 years of age, and the oldest, 90 years of age. Twelve of the patients