A procedure is described that permits the preparation of [18F]haloperidol in 140 min at specific activities ranging from 4-5 muCi mg-1. A key step in the synthetic route involves the incorporation of 18F into the molecule through a Schiemann-type reaction, which involves the pyrolysis of the diazonium tetrafluoroborate salt of 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4'-aminobutyrophenone.