The present invention relates to 15-cycloalkyl-prostaglandins of the formula: ##STR1## wherein A represents a grouping of the formula: ##STR2## W represents ethylene or trans-vinylene, X represents ethylene or cis-vinylene, Y represents ethylene or trans-vinylene, R represents a hydrogen atom or a straight- or branched-chain alkyl group containing from 1 to 12 carbon atoms, R.sup.1 represents a hydrogen atom or a methyl or ethyl group, R.sup.2 represents a straight- or branched-chain alkyl group containing from 2 to 8 carbon atoms or a phenyl group unsubstituted or substituted by an alkyl group containing from 1 to 3 carbon atoms, R.sup.3 represents a hydrogen atom or a straight- or branched-chain alkyl group containing from 1 to 3 carbon atoms, and n represents 4 or 5 and cyclodextrin clathrates of such acids and esters and, when R represents a hydrogen atom, non-toxic salts thereof.These new compounds exhibit characteristic prostaglandin-like activities.