Gastric neuroendocrine neoplasms of type 1 and type 3 are different entities and as such require different therapeutical strategies. The aim of this study was to define and distinguish these two tumour subtypes with clearly different biological properties and patient survival. As shown, serum gastrin is an important diagnostic tool for differentiating the less malignant type 1 "hypergastrinemia non-related" tumor from malignant type 3, along with other parameters of malignant potential such as proliferation index and depth of invasion.The biological behaviour, tumour marker status, symptomatology, survival and therapeutical strategy were assessed and compared in 18 consecutive patients with type 1 and 7 with type 3 gastric neuroendocrine tumours.All 18 patients with type 1 gastric carcinoids survived long-term. 17/18 patients were treated with endoscopic tumour removal. The prognosis for patients with generalized type 3 neuroendocrine neoplasms was poor, with short-term survival. No statistically significant differences between the types were found in urine 5-hydroxyindolacetic acid concentration or serum chromogranin A concentration. Significant differences were found in serum gastrin with high levels even in localized type 1 tumors and normal levels in generalized type 3 neoplasm. Further, high neuron-specific enolase levels were found in type 3.Type 1 tumour should be preferably treated with endoscopic tumour removal. Recently, favourable tumoristatic effects have been reported in somatostatin analogs. Surgery is a treatment option for type 3 neuroendocrine carcinoma with normal gastrinemia. Serum gastrin is suitable for assessment of the biological properties of both neuroendocrine neoplasm types. It serves, among other factors, as a predictor of prognosis and an indicator for the selection of optimal therapeutical strategy.