Between 1977 and 1989 46 patients with soft tissue tumors of the stomach were treated at the Department of Surgery, University of Heidelberg. Twenty-one tumors were malignant and 25 benign. Sixteen of 21 malignant and 13 of 25 benign tumors originated from smooth muscle. Surgical therapy consisted of local excision of the tumor with a margin of gastric wall, or partial gastrectomy. One patient required total gastrectomy for complete removal of the tumor. The adjusted 5-year survival of all 21 patients with malignant tumors was 71% calculated by life-table analysis. Prognostic factors were local invasion and distant metastases. None of 15 patients without local invasion or metastasis has died of disease at a mean follow-up of 3.1 +/- 0.7 years (range 0.1 to 5.8 years) and only one of these patients had tumor recurrence. Nucleolar organizer regions (NOR) were determined in 16 malignant tumors of myogenic origin. Low (less than 4.0/nucleus) NOR counts indicated good prognosis with an adjusted 5-year survival of 100% in 11 patients as compared to 30% for five patients with more than 4.0 NOR/nucleus. Complete removal of the tumor together with a 2-cm margin without radical lymphadenectomy appears to be adequate surgical treatment. The indications for adjuvant therapy in patients with curative surgery and the value of chemotherapy or radiotherapy for treatment of persistent or recurrent disease remain to be established. NOR studies may help to identify patients at high risk.