6-[18F]Fluoro-L-dopa was designed to trace the dopamine metabolism in the brain with positron tomography. 6-[18F]Fluoro-L-dopa resembles natural L-dopa biochemically, it crosses the blood-brain barrier with the similar kinetics, it is decarboxylated by dopa decarboxylase and is stored intraneuronally in vesicles. In addition the rate of O-methylation of 6-[18F]fluoro-L-dopa by catechol-O-methyl transferase is only 1/4 of that of natural L-dopa. The low rate of O-methylation, especially in the periphery, is particularly beneficial for PT investigations of the brain. The radiotracer has been synthesized using a variety of electrophilic fluorinating agents.