In this study, derivatives of 1-benzyl-2-substituted-4,5-diphenyl-1H-imidazole were synthesized and their analgesic activity assayed in two tests. 1,2,4,5-Tetrasubstituted imidazole compounds were obtained by the treatment of purified imidazole compounds with benzyl chloride in the presence of sodium hydride. The structure elucidation of the compounds was performed by IR, H-1-NMR and mass spectroscopic data and elemental analysis results. Generally the prepared compound exhibited only moderate analgesic activity in mice at the dose of 100 mg/kg i.p.; however, a few of them exhibited good activity, almost equivalent to that of morphine at 1 mg/kg i.p. was observed. At the above dosage, no toxicity was observed for all compounds. (C) 2001 Elsevier Science S.A. All rights reserved.