SummaryPityriasis versicolor is a relatively common skin disease in Western Australia. Four hundred and fifty cases were referred to the Mycology Laboratory for confirmation in the 10 year period 1963–1972. Since this series concluded we have seen approximately 200 cases each year. It is still more prevalent in Western Australia than these numbers indicate.Pityriasis versicolor is common in all age groups but is more common in healthy young adults. Most people with the infection have a high standard of personal hygiene. If occurs in both males and females. What really initiates infection is not clear; but in Western Australia it is most likely to be simply a matter of heat, sweating and genetic predispositio