A crystalline Form II of 17-N-[2,5-bis (trifluoromethyl)phenyl]carbamoyl-4-aza-5--androst-1-en-3-one (dutasteride) is provided. The preferred crystalline Form II of dutasteride has an X-ray powder diffraction pattern, expressed in terms of d-spacing (in A), with peaks at about 13.42, 6.96, 6.13, 5.27, 4.77, 4.70, 4.58, 4.46 and 3.82. A process for preparation of a crystalline Form II of dutasteride is also provided and includes dissolving a crude form of dutasteride in an alcoholic solvent having from 1 to 5 carbon atoms; removing the alcoholic solvent to obtain a residue; adding an ester solvent to the residue; and filtering the resulting separated solids. The processes of the invention are believed to be simple, eco-friendly, and commercially viable.