A 64-year-old male presented with progressive right-sided inguinal pain radiating to the right flank and lower back. He had noticed an infrequent altered sensibility on frontal parts of his right upper leg. Physical examination demonstrated the presence of a process in the lower abdomen. Computer tomography showed a retroperitoneal tumor with a 10 cm diameter that probably originated from the inferior caval vein (ICV). During an explorative laparotomy a tumor that was compressing the right N. genitofemoralis was radically removed together with the right kidney and the ventral wall of the ICV. The histological diagnosis was a radically removed leiomyosarcoma. Based on the clinical picture, diagnostic imaging and pathologic examination the diagnosis leiomyosarcoma ofthe ICV was confirmed. A leiomyosarcoma of the ICV is a rare tumor with atypical symptomatology and a slow growth rate often leading to a late diagnosis. Surgery is the only effective treatment. The prognosis is moderate.