Previous studies have suggested that the sensitivity of the ThinPrep Imaging System (TIS) for high-grade intraepithelial lesion (HSIL) and worse may be decreased at workloads above 100 slides/day. On the other hand, at a threshold of atypical squamous cells of undetermined significance (ASCUS) and above, sensitivity of the TIS appears to more closely correlated with epithelial cell abnormality (ECA)-adjusted workload (ECA rate × actual slides/day) rather than total workload. We sought to determine if the sensitivity of the TIS for HSIL could also be shown to be correlated with ECA-adjusted workload. The change in sensitivity for HSIL from manual screening to TIS screening consistently correlated negatively with ECA-adjusted workload both in the original Food and Drug Administration trial study and in independent studies available in the literature. Both sources suggest that sensitivity near 100% can be achieved with ECA-adjusted workloads of 5–7 slides/day. For a laboratory with an ECA rate of 10%, this represents a total workload of 50–70 slides/day. We conclude that measuring the ECA-adjusted workload is a valuable method to assess workload for the ThinPrep Imaging System. Diagn. Cytopathol. 2012. © 2010 Wiley Periodicals, Inc.