This technical paper examines the issue of attrition bias in two cohorts of the Longitudinal Surveys of Australian Youth (LSAY), based on an analysis using data from 1995 to 2002. Data up to 2002 provided eight years of information on members of the Y95 cohort and five years of information on members of the Y98 cohort. This study suggests that researchers using the LSAY data sets can be confident that the post-stratification and attrition weights ensure that the remaining sample members represent the population from which they were selected. If comparisons are to be made with concurrent data--such as a comparison between Year 12 completion rates in LSAY and apparent retention rates published by the Australian Bureau of Statistics--then researchers are advised to explain how the results differ and why they are not expected to be the same. Such an approach recognises the design of LSAY and the limitations of using LSAY for point-in-time estimates. A list of tables representing the numbers of sample members interviewed and attrition rates is appended. (Contains 6 footnotes, 15 tables, and 7 figures.)