Abstract: N-(2-substituted alkyl)-N'[(imidazole-4-yl)alkylguanidines are provided by the reaction of a primary amine with benzoylisothiocyante to a benzoylthiourea derivative, followed by hydrolysis of this derivative to form the corresponding thiourea, converting this thiourea with methyliodide into an isothiourea and producing the desired compound by reaction of the isothiourea with aminopropylimidazole or aminoethylimidazole. The compound can be converted into an acid addition salt or the free compound obtained from such salt. The compounds are useful as the active ingredient in pharmaceutical compositions for the treatment of congestion, heart failure and some allergic conditions.