Compounds of formula (I) are useful in the treatment of disease responsive to modulation of CRTH2 receptor activity, wherein: A represents a carboxyl group —COOH, or a carboxyl bioisostere; L1 is a bond, —CH2—, —OCH2—, —CH2CH2— or —CH═CH—; L2 is CONH—, —NHCO—, SO2NR1—, —NR1SO2 wherein R1 is hydrogen or C1-C3 alkyl, or a divalent radical of formula (X) or (Y), wherein ring Q is a non aromatic heterocyclic ring containing 5 to 7 ring atoms, including the nitrogen shown; L3 is a divalent linker radical of formula -(Alk1)m-(Z)n-(Alk2)p as defined in the description; ring Ar1 is an optionally substituted divalent phenyl radical or divalent 5- or 6-membered monocyclic heteroaryl radical, in which L1 and the H[B]sL3L2Ar2CONH-radical are linked to adjacent ring carbon atoms; ring Ar2 is an optionally substituted 1,3-phenylene radical, or an optionally substituted divalent 5- or 6-membered monocyclic heteroaryl radical, in which AL1Ar1NHCO-radical and the H[B]sL3L2-radical are linked to ring carbon atoms which are not in ortho relationship; ring B is as defined for Ar2, or an optionally substituted cycloalkyl, N-pyrrolidinyl, N-piperidinyl or N-azepinyl ring; and s is 0 or 1.