A study of hospital admissions of paediatric cases with asthma over a 17-year period (1971-1987) in Western Australia was performed retrospectively. Hospital admission rates for asthma increased in all paediatric age-groups with the most dramatic increase occurring in the youngest (zero- to four-years') age-group. This increase in hospital admissions for asthma has been accompanied by a rapid decline in admissions for other paediatric respiratory conditions that share a potential diagnostic overlap with asthma. Hospital admission rates for asthma have reached a plateau at the major paediatric teaching hospital in the State from 1977 and Statewide from 1983. Diagnostic transfer has contributed significantly to the reported increase in hospital admissions for asthma over the past two decades.