Prostaglandin analogues of the formula:- ##SPC1##Wherein A represents a PGF or PGE grouping, X represents ethylene or cis-vinylene, Y represents ethylene or transvinylene, R.sup.1 represents hydrogen or alkyl of 1 to 4 carbon atoms, R.sup.2 represents alkyl of 1 to 10 carbon atoms, or alkyl of 1 to 4 carbon atoms substituted by phenyl or cycloalkyl containing from 5 to 7 carbon atoms, or R.sup.2 represents a grouping of the formula:- ##SPC2##Wherein R.sup.3 represents alkylene of 1 to 4 carbon atoms, R.sup.4 represents oxygen or sulphur or sulphinyl, and R.sup.5 and R.sup.6 represent hydrogen, halogen, trifluoromethyl, alkyl of 1 to 3 carbon atoms are new compounds possessing pharmacological properties.