Abstract: In order to get some novel compounds with potent iNOS inhibitory activity, 12 target compounds of n-［4-(benzimidazole-2-thio)phenyl］-n′-alkyl guanidine derivatives (I₁-I₁₂) were synthesized from 1-benzoyl-3-［4-(benzimidazole-2-thio)phenyl］ thioureas (4) by hydrolysis with 2.0 mol·L^-1 sodium hydroxide solution containing tetrahydrofuran to form the corresponding n-［4-(benzimidazole-2-thio)phenyl］ thioureas (5) which was S-ethylated with ethyl iodide, followed by amination with primary amines or secondary amines. The intermediate 4 was synthesized from 2-mercaptobenzimidazole (1) by reaction with 1-chloro-4-nitrobenzene to form 2-(4-nitrophenylthio)benzimidazole (2) which was reduced by iron powder and hydrochloric acid, followed by reaction with benzoyl isothiocyanate. The structures of compounds I₁-I₁₂ were confirmed by IR, MS, 1H NMR and elemental analysis. The results of preliminary pharmacological test showed that the activities of three compounds (I₁, I₈ and I₁₀) were stronger than aminoguanidine, especially for compound I₁.