1,193,099. Estra-4,9,11-trien-3-one 17-carbonates. ROUSSEL-UCLAF. 14 Nov., 1967 [17 Nov., 1966], No. 51701/67. Heading C2U. Compounds of formula (wherein R is a cycloalkyl-alkyl group) are prepared by reacting the corresponding 17#- hydroxy compound with a cycloalkyl-alkyl haloformate in the presence of a tertiary base. Compounds of Formula I possess anabolic activity and may be made up with suitable vehicles into pharmaceutical compositions which may be administered parenterally or rectally.