Abstract: Therapeutically useful pyrrolo[2,1-a]phthalazine derivatives of the formula: ##STR1## wherein R.sup.1 and R.sup.2 represent cycloalkyl, optionally substituted alkyl, alkenyl, alkynyl, aryl or heteroaryl, X represents ethylene or vinylene, R.sup.3 represents a group of the formula:--Y--CH.sub.2 --CH(OH)--CH.sub.2 --COOR.sup.5wherein Y represents carbonyl or hydroxymethylene and R.sup.5 represents hydrogen or optionally substituted alkyl, or R.sup.3 represents a lactone ring and the symbols R.sup.4 represent hydrogen, halogen, optionally substituted alkyl, alkenyl, alkynyl, aryl or heteroaryl, or R.sup.6 O-- wherein R.sup.6 represents alkyl, aryl or arylalkyl and salts thereof, processes for their preparation and compositions containing them are described.