The X-ray structure of 6-methyl-3,20-dioxo-4,6-pregnadien-17α-yl acetate is reported. The crystals are monoclinic, space groupP21,Z=4,a=28.955(7),b=6.597(2),c=11.064(3) A,/gb=90.80(2) °. The two crystallographically independent molecules have very similar overall geometries. The A rings have intermediate sofa-half-chair conformations and are bent relative to the steroid skeleton. The conformation of the 17β-progesterone side chain is stabilized by the 17α-ester substituent; the C(16)-C(17)-C(20)-O(20) torsion angle is −19.4(6) and −20.6(7)°.