Treatment with antipsychotic drugs has been associated with hyperprolactinemia. The same antipsychotic drugs have also been associated with side effects such as menstruation disorders. The aim of this study was to evaluate the prevalence of hyperprolactinemia and menstruation disorders in women undergoing antipsychotic treatment. We performed a retrospective chart review study of psychiatric patients who underwent laboratory testing for serum prolactin (PRL) level between March 2011 and March 2015 in Ehime University Hospital. Patients presenting with and without menstruation disorders were evaluated to determine if they presented concomitant hyperprolactinemia. Patients with menstrual disorders had a significant increase in serum PRL level with a mean of approximately 90 ng/mL. Those with menstrual disorders presented increased PRL levels by 2-fold that of patients without menstrual disorder. However, there was no significant difference in the equivalent dose of chlorpromazine between these two groups. Additionally, about 70% of patients with menstrual disorders received risperidone treatment. The receiver operating characteristic curve showed that the optimal cutoff point of serum PRL level associated with the development of menstrual disorders was 60 ng/mL. Based on these results, we concluded that patients with menstrual disorders presented increased serum PRL, and that most of them underwent treatment with risperidone.