A class of 3-phenylimidazo(1,2-a)pyrimidine derivatives (of Formula I, or salt or prodrug thereof: I) wherein Y represents a chemical bond, an oxygen atom, or a —NH— linkage; Z represents an optionally substituted aryl or heteroaryl group; R1 represents hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano trifluoromethyl, nitro, —ORa, —SRa, —SORa, —SO2Ra, —SO2NRaRb, —NRaRb, —NRaCORb, —NRaCO2Rb, —CORa, CO2Ra, —CONRaRb or —CRa═NORb; and Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group.), substituted at the meta position of the phenyl ring by an optionally substituted aryl or heteroaryl group which is directly attached or bridged by an oxygen atom or a —NH— linkage, are selective ligands for GABAA receptors, in particular having good affinity for the a2 and/or a3 and/or a5 subunit thereof, and are accordingly of benefit in the treatment and/or prevention of adverse conditions of the central nervous system, including anxiety, convulsions and cognitive disorders.