A group of N-[(phenylcarbonyl)amino]1-2,3,6-tetrahydropyridines, 5, were synthesized to determine the effect that changes in aromatic substitution on the phenyl ring have on analgesic, hyperglycemic, and antiinflammatory activities. All of the N-[(phenylcarbonyl)amino]-1,2,3,6-tetrahydropyridines 5 exhibited potent analgesic activity, relative to morphine, irrespective of the position and physicochemical properties of the aromatic substituent. Pretreatment with naloxone did not alter the analgesic activity of the 4-fluorophenyl derivative 5P. N-[[(2-Fluorophenyl)-carbonyl]amino]-1,2,3,6-tetrahydropyridine (5n) was one of the most active hyperglycemic agents, elevating blood glucose 213 and 127% at 2 and 4 h after a 100 mg/kg po dose. Incorporation of aromatic substituents into the 3 and 4 positions of 1 abolished antiinflammatory activity.