The diffusion of new medical technologies is often described as rapid, widespread and premature. Such characterizations have arisen largely from studies undertaken in the U.S. The extent to which these patterns can be generalized to the Canadian context is not yet clear. This paper examines the diffusion of genetic amniocentesis in relation to its adoption and utilization in Ontario. Slow and limited institutional adoption of amniocentesis and substantial increases in its use at several centres offering the procedure reveal differences with and similarities to the U.S.-based model. Possible explanations of these differences and the public policy implications of the findings are discussed.