Retroperitoneal perforation of diverticular disease is very uncommon and can be difficult to diagnose because of possible pathways of communication between the retroperitoneal space and the thigh. An iliopsoas abscess from a ruptured diverticulum may drain into the hip joint if the capsule has been violated. Cases of abscesses or gas in the thigh have been reported in which thigh pain was the predominant symptom, overshadowing any abdominal signs. We report a case in which hip sepsis due to a ruptured diverticulum was the presenting feature.