Cystic seromas, or mature fibrous cysts, are rare complications after ventral and incisional hernioplasties employing polypropylene mesh. We analyzed the medical records of patients, whose abdominal-wall hernias were surgically repaired with polypropylene mesh from November 1996 to February 2004 (N=685). Of the 162 patients, who had incisional hernias repaired with the Rives technique (preperitoneal mesh), we detected two patients who developed giant cystic seromas. Both patients underwent surgical resection of the cyst wall. As follow-up care improves for patients undergoing hernioplasties with polypropylene meshes, more cystic seromas are detected, thereby improving our knowledge of the clinical, radiological, and histopathological characteristics of this complication. However, the etiologic factors related to the appearance of this chronic cyst remain uncertain.