A total of 121 consecutive patients with midgut carcinoid tumors underwent regular clinical control and 158 laparotomies for abdominal symptoms with 1 to 11 years (mean 5.2 years) of follow-up. Metastases were present in 93% of the patients at study inclusion and developed at initially uninvolved sites with an overall probability of 0.38. Patients without initial tumor spread developed mesenteric or liver metastases with the probability of 0.25 (mean delay 12 years), whereas those with mesenteric metastases exhibited a probability 0.56 to develop liver metastases (mean delay 6.1 years). Spread to extraabdominal sites in patients with mesenteric and liver metastases exhibited a probability of 0.22 (mean delay 4.3 years), and this spread was especially frequent (probability 0.60) in patients with only liver metastases at inclusion. Patients without the carcinoid syndrome (52%) mainly suffered from more or less episodic abdominal pain, nausea, and diarrhea. Marked mesenteric fibrosis detected at surgery (n = 59) generally was accompanied by symptoms of abdominal pain and weight loss, and it often required urgent intervention due to intestinal obstruction or ischemia. Complete or partial symptom alleviation was accomplished in 82% of the operated patients, and generally was most auspicious after primary acute or subacute procedures (n = 54). The complete or partial symptom improvements after surgery lasted for mean 5.3 years and tended to be longer after elective (n = 50) than acute operations. The findings substantiate encouraging results of laparotomy in a compromised cohort of patients with midgut carcinoid tumors. Because the patients also displayed a generally slow progression of metastases, liberal indications for laparotomy should prevail in symptomatic and possibly also asymptomatic individuals with midgut carcinoid tumors.