Metoclopramide (MCP) is a selective blocker of dopamine D2 receptor, responsible for the dopamine inhibition of prolactin (PRL) secretion from the pituitary. In normal conditions, administration of the proper dose of MCP leads to increase of PRL concentration in the blood serum. This response was applied in the diagnostic test (MCP test), useful to differentiate between hyperprolactinaemia linked with organic causes (prolactinoma and other lesions of hypothalamo-pituitary region) and so-called functional hyperprolactinaemia. However, recently the value of this test is a subject of controversy. Because of that we evaluated the usefulness of MCP test in our clinical material. We analyzed 228 patients with hyperprolactinaemia, hospitalized in the Department of Clinical Endocrinology, Medical University of Lodz, in 2006. In all patients, MCP test and magnetic resonance imaging (MRI) were performed. In 48 (21%) patients, the pathological changes in MRI (pituitary macro- and microdenomas, pituitary stalk suppression) were found and these patients were included to the organic hyperprolactinaemia group. The remaining 180 (78.9%) patients without alterations in MRI were included to the group of functional hyperprolactinaemia. The administration of MCP in patients with pituitary tumors and with stalk suppression induced the slight increases of PRL concentration in 60 min of the test (30 and 40%, respectively). In patients with functional hyperprolactinaemia, a sharp increase of PRL concentration (usually over 300%) was found. These results indicate that the MCP test possesses the diagnostic value and may be usefull especially in cases with marked basal levels of PRL.