Three pregnane-type steroids, including a new metabolite, 3 beta-methoxy-5,20-pregnadiene (1) along with two known analogues, 3 beta-acetoxy-5,20-pregnadiene (2) and 5 alpha-pregna-1,20-dien-3-one (3) were isolated from the soft coral Scleronephthya flexilis. Standard spectroscopic techniques were used to determine the structure of new steroid 1. The absolute stereochemistry of steroid 2 was confirmed by X-ray diffraction analysis. Steroid 3 exhibited potent activity against MOLT-4 tumor cells.