This paper explores chronologically the evolution of raised prolactin levels as an entity in psychiatric patients. Menstrual problems were described in patients with schizophrenia prior to the introduction of antipsychotic medication, but galactorrhoea and gynaecomastia were not commonly seen until the advent of antipsychotics. Following the introduction of antipsychotic medication single case reports of patients with galactorrhoea and gynaecomastia appeared. These were followed by a collection of case reports and the process reached today's data of laboratory defined rates of prolactin and sexual side effects. The paper also reviews the emerging research linking hyperprolactinaemia with increased risk of osteoporosis and possibly breast cancer. An overarching thread which runs throughout these publications, is the paucity of clinical research, which has only recently begun to be addressed.