Lodging of cardiovascular gas bubbles is investigated in a microfluidic model of small arteriole bifurcations. This work is motivated by a novel gas embolotherapy technique for the potential treatment of cancer by tumor infarction and by air embolism. The experimental model arteriole bifurcations were constructed from a transparent elastomer, poly(dimethylsiloxane), using soft lithography. A single air bubble was suspended in water within the parent tube of the bifurcation and a specified driving pressure was imposed via constant elevation reservoirs that were open to atmospheric pressure. The driving pressure and bubble size were varied, and their effects on the bubble lodging were assessed. These findings may be useful in developing strategies for microbubble delivery in gas embolotherapy.