Abdominal malignant tumors with a mono- or multivisceral involvement have a poor prognosis. Surgery is the only treatment with a hope to be curative. Between January 1989 and December 1992, 30 patients (12 men, 18 women, mean age 67.9) with abdominal malignancy involving one or more adjacent organs were operated on at the Department of Surgery, General Hospital, La Chaux-de-Fonds, Switzerland. The majority of the tumors originated from the colon and rectum. 64 organs were partially or totally resected. Every curative procedure consisted of an "en bloc" resection. 53% of the procedures were curative, 37% palliative and 10% explorative. Surgical morbidity reached 30% and hospital mortality 13% (one peroperative death). Surgery obtained a local control of the tumor in 75% of the cases. After curative procedures, local recurrence and secondary metastases appeared respectively in 25% and 19% of the cases. After a palliative operation, preoperative symptoms diminished or disappeared in 82% of the patients. Tumor curability essentially depends on invaded organs. Mobile organs can nearly always be excised. Non-mobile organs and retroperitoneum are resected much more difficultly. Surgical treatment of multiorgan malignancies is difficult. It involves a long and tenacious exploration before declaring the tumor non-resectable.