Spigelian hernia may be a more common clinical entity than previously recognized or reported. We report seven cases, four diagnosed and treated in the past 12 months at a large military hospital. Diagnosis can be difficult because of failure to consider it, incomplete understanding of the anatomy, and the nonpalpable intraparietal nature of the hernia. A careful history and physical examination are essential. Any patient with persistent localized pain in the proper anatomic location--just lateral to the outer border of the rectus muscle and usually below the umbilicus--warrants surgical exploration.