In the present study we investigated whether a correlation exists between menstrual cycle phase on the day of an acute psychiatric admission and diagnostic entities. Therefore we assessed the menstrual cycle phase in 155 women at the time of acute admission for any non-organic psychiatric disorder. A specific diagnosis according to ICD-10-criteria and to Leonhard's nosology was established without knowledge of the menstrual cycle phase. Independent of diagnosis and classification, the majority of patients (57%) was admitted during the pre-menstrual/menstrual period. Comparing the frequencies of admission before (increasing blood-estrogen-level) and after ovulation (decreasing blood-estrogen-level) we found using ICD-10 criteria there were no significant differences between affective psychoses (F3), acute polymorphous psychotic disorder (F23), schizophrenia/schizoaffective psychoses (F20 and F25) and patients suffering from neuroses or personality disorders (F4-F6). Applying Leonhard's criteria we found no significant differences between endogeneous psychoses and personality disorders and no significant differences between cycloid psychoses and affective psychoses or affective psychoses and schizophrenias as well. However, patients with cycloid psychoses were significantly more frequently admitted to hospital during the luteal-/menstrual phase than patients with schizophrenia (chi 2-Test, p = 0.02). These findings do not confirm a specificity of a pre-menstrual exacerbation of psychotic symptoms for schizophrenia. Rather we found cycloid psychoses to be significantly more frequently associated with premenstrual exacerbation of symptoms.