The invention relates to new 1,2,3,4,6,7,12,12b-octahydroindolo[2,3,-a]quinolizin-1-yl-alkanecarboxylic acid amides of the formula (I), ##STR1## wherein R.sub.1 and R.sub.2 stand independently for a hydrogen or halogen atom, or a hydroxyl, nitro or C.sub.1-4 alkoxy group;R.sub.3 and R.sub.4 stand independently for a hydrogen atom or a C.sub.1-4 alkyl group;R.sub.5 and R.sub.6 stand independently for a hydrogen atom, C.sub.1-8 alkyl group, C.sub.3-8 alkenyl or cycloalkyl group, aryl or aralkyl group, heteroaryl or heteroaralkyl group containing oxygen, nitrogen or sulphur atom, all these groups being optionally substituted; orR.sub.5 and R.sub.6 together form an optionally substituted C.sub.2-8 .alpha.,.omega.-alkylene group, wherein one carbon atom may optionally be replaced by an oxygen or nitrogen atom; andG means a C.sub.1-4 straight chained alkylene group, as well as to their therapeutically suitable acid addition salts and pharmaceutical compositions containing these compounds. The compounds of the formula (I) have valuable therapeutic properties, namely vasodilatory, spasmolytic, antiarrhythmic and gastrocytoprotective effects. The gastrocytoprotective effect is particularly important.