The present work reports on the synthesis and preliminary pharmacol. investigation of new 3-​aryl-​6,​7-​dimethyl-​9-​substituted thiazolo[3,​2-​a]​benzimidazolium salts.  These derivs. were synthesized by reacting the 3-​aryl-​6,​7-​dimethylthiazolo[3,​2-​a]​benzimidazoles with the appropriate quaternizing agent.  The latter compds. were, in turn prepd. by cyclodehydration of 5,​6-​dimethyl-​2-​(phenacylthio)​benzimidazoles in polyphosphoric acid (PPA)​.  The latter derivs. were obtained by the reaction of 5,​6-​dimethylbenzimidazole-​2-​thione with the appropriate phenacyl bromide.  Some of the tested compds. have shown a pronounced hypoglycemic activity.  The results do permit the assignment of compds. having N9-​phenacyl entity as promising antidiabetic agents.