Abstract: Prostaglandin E.sub.1 analogues of the general formula: ##STR1## [wherein Y represents ethylene or trans-virylene, Z represents ethylene or trans-vinylene, R.sup.1 represents a hydrogen atom, an alkyl group containing 1 to 12 carbon atoms, an aralkyl group containing from 7 to 12 carbon atoms, a cycloalkyl group containing from 4 to 7 carbon atoms and unsubstituted or substituted by at least one alkyl group containing from 1 to 6 carbon atoms, a phenyl group unsubstituted or substituted by at least one chlorine atom, trifluoromethyl group, alkyl group containing from 1 to 4 carbon atoms or phenyl group, a--C.sub.m H.sub.2m COOR.sup.5 group (wherein m represents an integer of from 1 to 12 and R.sup.5 represents a hydrogen atom or an alkyl group containing from 1 to 4 carbon atoms ), a --C.sub.n H.sub.2n OR.sup.6 group (wherein R.sup.6 represents a hydrogen atom or an alkyl group containing from 1 to 4 carbon atoms and n represents an integer of from 2 to 12), or a ##STR2## group (wherein R.sup.7 and R.sup.