This paper reviews the existing comparative literature with regard to differences and similarities of policy diffusion between democratic and authoritarian regimes. There has been an extensive discussion of causes and effects of policy diffusion for democracies, but the literature on autocracies lacks similar focus and scope. Similarly, research on the patterns and causes of policies’ diffusion across regime types is virtually non-existent. After some theoretical considerations about regime effects on diffusion in the first part of this paper, we analyse data on foreign trade regulations and nuclear power plants and compare results across regime types. Based on cross-time cross-section regression models, we can show that, depending on the specific policy field, regime type is of less importance for diffusion processes than theoretically expected. This highlights a need for further detailed research on the general role of regime type regarding policy diffusion.