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Arrangement and ultrastructural morphology of testicular capillaries were investigated in man, in the rat and in the bull. In these three subjects, we consistently found a rope-ladder-shaped capillary arrangement: Within the central parts of the interstitial spaces the precapillary vessels and interstitial capillaries, as well as the Leydig cells surrounding them and the interstitial venoles are located. The interstitial capillaries and venoles run approximately parallel to the tubuli contorti. They are connected by transversal capillaries running across part of the circumference of the tubules. In the light microscope, these vessels seem to have direct contact with the tubuli. The electron microscopic investigation shows that there is always a small space between the transversal capillary and the membrana propria of the tubules contortus. All these capillary vessels have continuous basal membranes and continuous nonfenestrated nonporous endothelia. Groups of “endothelial microvilli” are special structural differentiations of these capillary vessels.—The lymphatic vessels are situated in the peripheral portions of the interstitia. In our material, they begin with peritubular networks of closed capillaries with mostly nonporous and nonfenestrated endothelia. Partially, these vessels have no continuous basal membrane. They have a very tender connective tissue anchoring.