Tiospirone (BMY-13,859), also sometimes called tiaspirone or tiosperone, is an atypical antipsychotic of the azapirone class.

[1] It was investigated as a treatment for schizophrenia in the late 1980s and was found to have an effectiveness equivalent to those of typical antipsychotics in clinical trials but without causing extrapyramidal side effects.

[2][3][4][5] However, development was halted and it was not marketed.

Perospirone, another azapirone derivative with antipsychotic properties, was synthesized and assayed several years after tiospirone.

[6] It was found to be both more potent and more selective in comparison and was commercialized instead.