The respective lengths of hospital stay of aboriginal and non-aboriginal children between 1971 and 1979 were studied using the Western Australian Hospital Morbidity Data Collection. In each of the years studied, the median length of hospital stay of aboriginal children was at least twice as long as that of non-aboriginal children, irrespective of hospital type, age at admission to hospital, sex, the region of home address or the category of disease. However, an encouraging decline in the length of hospitalisation of children from both racial groups was observed over the study period; this decline was more marked in aboriginal children. Nevertheless, in 1979, the excess hospitalisation of aboriginal children still accounted for 30,000 bed-days in Western Australian hospitals, and is estimated to have cost $4,900,000. It is recommended that aboriginal liaison officers be employed to reduce this cost, and to mitigate other problems associated with the hospitalisation of aboriginal children.