The invention relates to a new process for the treatment of hypertension and thromboembolic diseases in humans by simultaneous administration of (.+-.)- or (-)-2-[1-(2,6-dichlorophenoxy)-ethyl]-1,3-diazacyclopent-2-ene hydrochloride on the one side, and 4,5-dihydro-6-[4-(1-imidazolyl