Patients with serotonin-containing metastatic midgut carcinoid tumours were treated with temporary liver dearterialization (19 patients) or liver embolization (8 patients). After 3, 6 and 12 months the effects of treatment were registered in changes in serotonin in platelet-poor plasma and blood, in urinary 5-HIAA, in tumour extent in the liver and in symptomatic relief. Seventeen patients, who underwent the dearterialization procedure survived the operation, while 2 patients who had a concomitant small bowel resection died of complications. Tumour response was obtained in 8 patients after 6 months and in 9 patients after 12. Stable disease was noted in 5 patients after 6 months and 3 patients after 12 months. Progressive disease was seen in 4 patients. All 19 patients except one exhibited the carcinoid syndrome prior to operation and 11 patients were free from symptoms for at least 12 months postoperatively. The gelatine foam powder liver embolization was performed uneventfully in all 8 patients. Tumour response was obtained in 3 patients at both 3 and 12 months. Stable disease was noted in 5 patients at 3 months and 4 patients at 12 months. Before embolization the patients suffered from the carcinoid syndrome and the treatment resulted in the immediate disappearance of the syndrome in 5 patients. After 12 months one patient was still free from obvious carcinoid symptoms. In one patient the disease aggravated in spite of treatment and he died 5 months after embolization. Thus, temporary liver dearterialization and liver embolization in midgut carcinoid patients resulted in tumour regression and symptomatic relief in 9 out of 19 patients and 3 out of 8 patients respectively. The complication rate was low.