A prospective study has been performed on 84 patients with endocrine pancreatic tumours evaluated at the Medical Department in Uppsala. Available information concerning the patients' presenting symptoms, age at diagnosis, clinical syndrome, tumour location, location of metastases, diagnostic radiology, biochemical and histopathological findings has been analysed. Our results indicate that most patients initially show rather vague and non-specific symptoms, with dyspepsia and pain being the most frequent presenting features. The median delay between appearance of the first symptom and diagnosis was 2 years; the delay was 35 months in sporadic cases and 14.5 months in familial cases. In spite of improvements in diagnostic methods, the median age at diagnosis (53 years) has not been reduced, and most patients are encountered when the tumour has reached an advanced stage. There is a need for a method of screening patients with still uncharacteristic abdominal symptoms for a neuroendocrine tumour. The presence of elevated levels of plasma chromogranin in all patients with a proven tumour suggests that such possibilities exist, and the use of this biochemical marker in the future might reduce the age at diagnosis and thus improve the likelihood of cure and survival of patients with endocrine pancreatic tumours.