The aetiological fraction methodology and the associated fraction estimates enable estimation of the proportion of cases of an illness or injury that can be attributed to a risk factor. This report presents aetiological fraction estimates attributing deaths and hospital separations resulting from a range of specific illnesses or injuries to tobacco, alcohol and illicit drugs. The fractions represent a revision of the fractions originally presented by Holman et al. (1990) and later revised by English et al. (1995). Also presented here are estimates of 1998 mortality and 1997–98 hospital separations attributable to alcohol, tobacco and illicit drugs based on the revised fractions.