Azaprostacyclins of Formula I ##STR1## wherein R.sub.1 is hydrogen, alkyl, cycloalkyl, aryl, a heterocyclic residue, or a phenacyl residue optionally substituted on the phenyl ring by bromine, phenyl, alkoxy, or dialkoxy,W is a free or functionally modified carbonyl group or a ##STR2## wherein R.sub.8 is hydrogen or alkyl of 1-5 carbon atoms and R.sub.9 is hydrogen or a readily cleavable ether or acyl residue and wherein the OR.sub.9 -group can be in the .alpha.- or .beta.-position,R.sub.2 is a free or functionally modified hydroxy group,R.sub.3 and R.sub.4 each independently is hydrogen, alkyl of 1-5 carbon atoms, or fluorine,D is alkylene of 1-2 carbon atoms which can be substituted by alkyl groups of 1-5 carbon atoms,R.sub.5 is hydrogen or alkyl of 1-2 carbon atoms or, when D is alkylene of 1 or 2 carbon atoms, R.sub.5, together with R.sub.6, represents a bond,R.sub.6 and R.sub.7 each independently is hydrogen or alkyl of 1-2 carbon atoms, whereinR.sub.6 (R.sub.7) is halogen when R.sub.7 (R.sub.6), respectively, is alkyl of 1-2 carbon atoms orR.sub.5 and R.sub.7 each independently is hydrogen or alkyl of 1-2 carbon atoms whenD and R.sub.6 together form a carbocyclic ring closed via (CH.sub.2).sub.1-3 with D as --CH