summaryThe compound Ro 19-6327, N-(2-arninoethyl)-5-chloropyridine-2-carboxmide, is known to inhibit reversibly and site specifically the enzyme monoamine oxidase B (MAO-B). The 1231-labelled iodo-analogue N-(2-aminoethyl)-5-iodopyridine-2-carboxamide (Ro 43-0463) was investigated successfully in human volunteers by means of SPET (Single Photon Emission Tomography). We developed therefore the synthesis and radiolabelling of the corresponding fluoro-analogue N-(2-aminoethyl)-5-fluoropyridine-2-carboxamide with ISF in order to carry out PET (Positron Emission Tomography) investigations of MAO-B related neuropsychiatric diseases. For this purpose two synthetic approaches leading to the electrophilic and the nucleophilic methods of ' SF radiolabelling were undertaken. The nucleophilic approach appeared to be superior when factors such as precursor synthesis, beam time, specific activity and radiochemical purity of the product are considered.