Umbilical cord blood is a rich source of blood stem cells, which are of critical clinical importance in the treatment of a variety of malignant and genetic conditions requiring stem cell transplantation. Many countries have established national public cord blood banks; such banks often coexist with a panoply of private options for cord blood banking. Until recently, Canada was the only G8 country without a national cord blood bank. This differs markedly from the United States, which years ago established a national cord blood bank policy and inventory. This article investigates potential reasons for this discrepancy through a comparative analysis of the evolution of programs and policies on national cord blood banking in Canada and the United States. My analysis suggests that cross-national discrepancies in policy on public cord blood banking were determined primarily by institutional factors, principal among them formal governmental structure and the legacy of past policies. Institutional entrepreneurialism in the health sector played a constitutive role in the earlier evolution of national cord blood policy in the United States as compared to Canada.