AbstractThe crystal structure of methyl‐16, nor‐5‐hydroxy‐6,7,15‐trioxo dehydroabietate has been determined from three‐dimensional X‐ray diffraction data. The compound crystallizes in the orthorhombic space group P21212 with unit cell parametersa= 19.226(3) Å,b= 11.075(3) Å,c= 8.375(2) Å,Z= 4,V= 1783.3(7) Å3,d0= 1.36 gcm−3. The gross structure was determined by direct methods which on refinement yielded a final value ofRindex as 0.038. Ring A is a chair, ring B an envelope whereas the ring C adopts a strictly planar conformation. The rings A and B aretransfused. The ester group at C4 iscisfused to methyl carbon C15 whereas another methyl carbon C18 andoxoO(15) of the isopropyl group at C13 are rotated to positions 0.107(3) Å and 0.179(2) Å out o