Azetidinone compounds of formula (I) in which inter alia: R?0 is CR4R5-X1-Y1¿ or (CH¿2?)pX?2(CH¿2)qY?2; R4 and R5¿ which may be the same or different is each selected from hydrogen and C¿(1-6)?alkyl, or R?4 and R5¿ may be linked together to form the residue of a C¿(3-7)?cycloalkyl ring; X?1¿ is a linker group and Y1 is optionally substituted C¿(1-12)?alkyl C(2-12)alkynyl, C(2-12)alkynyl, C(3-7)-cycloalkylC(1-8) alkyl or an optionally substituted heteroaryl group; and X?2¿ is a heteroaryl group and Y2 is an optionally substituted aryl group, p is an integer from 1 to 6, q is 0 or an integer from 1 to 6; are inhibitors of the phospholipase A2 enzyme Lp PLA2 and are of use in therapy, for instance in treating atherosclerosis.