Abstract: New benzimidazole derivatives of the general formula (I) ##SPC1##and acid addition salts thereof, whereinR.sub.1 and R.sub.2 each represent hydrogen or methyl,R.sub.5 and R.sub.6 form together a valence bond and at the same time R.sub.3 and R.sub.4 form together a group of the general formula (II), ##EQU1## wherein n is equal to zero or one, or R.sub.4, R.sub.5 and R.sub.6 form together a group of the formula (III) ##EQU2## and at the same time R.sub.3 stands for benzyl group, were prepared by reacting a compound of the general formula (IV), ##SPC2##wherein R.sub.7 stands for hydrogen or benzyl group and R.sub.1, R.sub.2 and n each have the same meanings as defined above, or an acid addition salt thereof with epichlorohydrine optionally in the presence of a base.The new compounds of the general formula (I) and their acid addition salts inhibit the reproduction of viruses and can be used in therapy as antiviral agents.