We investigated superficial interarterial, intra-arterial, arterio-venous and veno-venous anastomoses in 100 hearts from men and women taken at random who died at 20–85 years of age. By means of careful dissection and injection into the blood vessels of a differently stained 12% solution of vinilit in acetone, we studied the number and localization of the anastomoses and their appearance. Interarterial anastomoses, i.e. anastomoses between the ramification of the left and the right coronary artery, were detected in 33 hearts. Intra-arterial anastomoses, i.e. anastomoses between the ramifications of one and the same artery, were seen in 5 hearts. Arterio-venous anastomoses were found in 39 hearts. Veno-venous anostomoses were found in 49 hearts. The veno-venous anastomoses display a great many variations, being commonly the regular finding in human vein