Insul(in)oma is a usually solitary or, in some cases, multifocal tumor of pancreatic beta cells. It may be a component of multiple endocrine neoplasia type 1. or von Hippel-Lindau syndrome. In typical forms the diagnosis - based on the Whipple triad - is simple, however, it may be difficult to recognize in cases with near normal or only slightly elevated serum insulin levels, as well as in patients with known convulsive episodes. With the case presentation of an 81-year-old woman the authors draw attention to the pitfalls of the correct diagnosis. A special feature of the presented case is that convulsions persisted after surgical removal of the pancreatic neuroendocrine tumor verified with functional and imaging methods. Recurrent or residual tumor was not found, and morphological damage of the brain was absent. In the background of the continuing convulsions cerebrovascular alterations as well as the cytotoxic effect of the hypoglycemia-induced excessive glutamate production can be postulated.