OBJECTIVES: To investigate changes in incidence of admissions for schizophrenia and related non-affective psychoses in North Wales. DESIGN: Data from two epidemiologically complete cohorts of patients presenting for the first time to mental health services in North Wales between 1875-1924 and 1994-2010 are used in this study to map the incidence of hospital admissions for schizophrenia and non-affective psychoses. SETTING: The North Wales Asylum Denbigh (archived patient case notes) and the North West Wales District General Hospital psychiatric unit. POPULATION: 3168 patients admitted to the North Wales Asylum Denbigh 1875-1924 and 355 patients admitted to the District General Hospital psychiatric unit 1994-2010. RESULTS: There was an increasing admission incidence for schizophrenia between 1875 and 1900, a higher admission rate in the 1990s for males, followed by a drop in rates of admission for both genders since 2006. Admission incidences switch from parity between the sexes in the historical period to a doubling of the admission rates for men compared to women in the modern period. This admission pattern differs from the admission patterns for affective psychoses or organic disorders. CONCLUSION: There have been changes in the incidence of admissions for schizophrenia in North Wales.