5-HT1A receptors have long been implicated in the pathogenesis and treatment of anxiety and depressive disorders. Recently, several lines of studies have revealed new insights into the therapeutic role of 5-HT1A receptors in treating schizophrenia and Parkinson's disease. Specifically, 5-HT1A receptors seem to be a promising target for alleviating antipsychotic-induced extrapyramidal side effects (EPS) and cognitive/affective disorders in schizophrenia. In the treatment of patients with Parkinson's disease, 5-HT1A agonists are expected to improve not only affective symptoms (e.g., anxiety and depression), but also the core parkinsonian symptoms as well as antiparkinsonian agents-induced side effects (e.g., L-DOPA-induced dyskinesia). Here, the therapeutic mechanisms mediated by 5-HT1A receptors in schizophrenia and Parkinson's disease are reviewed. This evidence should encourage discovery of new 5-HT1A ligands, which can resolve the unmet clinical needs in the current therapy.