Objective: The purpose of the present study was to determine whether t
here was a significant seasonal variation in the birth dates of patien
ts with schizophrenia born in Tasmania. Method: The season of birth in
Tasmanian-born patients with schizophrenia (n=1412), born between 191
9-1970, was compared with general population data. Results: No signifi
cant variation in month or quarter of birth was detected for the subje
cts with schizophrenia, Neither was there any significant seasonal exc
ess when data from different decades were analysed separately, nor for
subsidiary analyses of gender or paranoid/non paranoid subtype. Concl
usion: These results are compared with those of six other published st
udies of Australasian-born subjects identified through registers in di
fferent States. While both positive and negative results are reported,
no clear pattern emerges, The relevance of season of birth to the dev
elopment of schizophrenia in Australia remains an open question.