Spigelian hernias may be more common than we think and are probably under-diagnosed. They commonly arise above the arcuate line. We describe three clinical stages: Stage 1 hernias are those without peritoneal sacs and tend to arise in younger patients, can be difficult to diagnose and may not seen at laparoscopy. Stages 2 and 3 hernias arise in older patients, do have peritoneal sacs, are visible at laparoscopy and are more likely to present as emergencies. Stage three hernias are too large for laparoscopic repair. The differences between stages likely reflect the natural history of the condition, which begins as extraperitoneal fat protrusion and progresses over many years to develop a peritoneal sac.