Hand hygiene is undoubtedly the most important strategy in combating the increasing incidence and debilitating effects of multidrug-resistant organisms in healthcare. Research on effective approaches for increasing compliance with hand hygiene is imperative, but the first step is to identify how to reliably and validly measure hand hygiene. This article examines publications between the years 1990 and 2006 that address measures of hand hygiene. The findings indicate that further research is needed to identify reliable and valid measures of hand hygiene.