This paper empirically examines the diffusion of hospital information systems (ISs), specifically, pharmacy, laboratory, and radiology systems. Given the policy significance of health IS and the widespread perception that it's diffusion is slow, a better understanding of the mechanisms driving IS adoption is needed. A novel data set incorporating both IS adoption and hospital characteristics was constructed. These data follow the behavior of 1965 hospitals for the years 1990–2000. Hypotheses pertaining to hospital characteristics, hospital competition, and strategic behavior are tested utilizing proportional hazard models. I find that IS adoption is related to multi-hospital system membership, payer mix, and hospital scale. The role of scale, however, significantly diminishes throughout the time period, likely reflecting improved personal computer performance and improved IT scalability. Conversely, I find little that strategic behavior or hospital competition affects IS adoption. Likewise, hospital ownership does not affect the adoption of these systems. Overall, these results suggest that hospital IS diffusion has not been normatively slow. Copyright © 2007 John Wiley & Sons, Ltd.