Not only being the mainstay of treatment for schizophrenia spectrum psychotic disorders, antipsychotics, especially the second-generation antipsychotics (SGAs) have also been recommended as augmenting agents for treating depression. Dopaminergic agents, including both dopamine D2/D3 antagonists and dopamine partial D2 agonists, have been effective for treating psychosis and schizophrenia. Amongst all SGAs, those with partial D2 agonistic property are generally acknowledged to have better side-effect profiles with lower incidence of extrapyramidal side-effects, prolactin increase, weight gain, QTc prolongation, and metabolic syndrome, as well as more efficacious in alleviating depressive symptoms. Up-to-date, three SGAs, namely aripiprazole, brexpiprazole and cariprazine, are known to possess such partial D2 agonism. ReSD-HK study is part of the ReSD Asian Study aiming to carefully evaluate a cohort of patients prescribed with brexpiprazole on its efficacy and tolerability as treatment for schizophrenia and/or depression in a real-life clinical setting.