Background . Illness-related presenteeism (suboptimal work performance) may be a significant factor in worker productivity. Until now, there has been no generally accepted best method of measuring presenteeism across different industries and occupations. This study sought to validate the Health and Work Performance Questionire (HPQ)-based measure of presenteeism across occupations and industries and assess the most appropriate method for data alysis. Methods . Work performance was measured using the modified version of the HPQ conducted in workforce samples from the education and health workforce in Queensland, Australia (N = 30,870) during 2005 and 2006. Three approaches to data alysis of presenteeism measures were assessed using absolute performance, the ratio of own performance to others' performance, and the difference between others' and own performance. The best measure is judged by its sensitivity to changes in health indicators. Results . The measure that best correlated to health indicators was absolute presenteeism. For example, in the health sector, correlations between physical health status and absolute presenteeism were 4 to 5 times greater than the ratio or difference approaches, and in the education sector, these correlations were twice as large. Using this approach, the estimated cost of presenteeism in 2006 was $Aus8338 and $Aus8092 per worker per annum for the health and education sectors, respectively. Conclusions . The HPQ is a valid measure of presenteeism. Transforming responses by perceived performance of peers is unnecessary as absolute presenteeism correlated best with health indicators. Absolute presenteeism was more insightful for ascertaining the cost of presenteeism.