Serotonin (5-hydroxytryptamine, 5-HT) is one of the most attractive targets for medicinal chemists. Among 5-HTRs, the 5-HT1A subtype is the best studied and it is generally accepted that it is involved in psychiatric disorders such as anxiety and depression. Several structurally different compounds are known to bind 5-HT1AR sites. Among these, arylpiperazine derivatives represent one of the most important classes of 5HT(1A)R ligands. This article will review the development of arylpiperazine derivatives acting at 5-HT(1A)Rs with an emphasis on structure-affinity relationships of agonists and antagonists, ligand-receptor interactions and pharmacological applications.