Microelectrode recording techniques and the anterograde transport of tritiated amino acids (TAA) were utilized to demonstrate the projections of AI, AII, and the anterior auditory field (AAF) to the inferior colliculus (IC). Microinjections of TAA into AI resulted in two restricted, labeled laminae in the central IC of both sides: one in the dorsomedial division of the central nucleus (ICC) and one in the pericentral nucleus (ICP). The location and orientation of the projection arrays, as a function of the best frequencies of the cortical injection sites, were consistent with best frequency‐position data obtained in microelectrode mapping studies in the ICC. With injections in AII near the border of AI, very sparse, diffuse labeling in ICP and in the dorsal and medial aspect of IC was observed. No projection to IC was observed in four AAF cases. These results indicate that (1) of these three fields, AI has the greatest descending input to IC; (2) the projection from AI is topographic (cochleotopic); and (3) the projections to the dorsomedial division of ICC are laminar and the position and orientation of the the laminae are appropriate with their being continuous with the morphologically laminated ventral lateral division. [Supported by NIH grant NS‐10414.]