The entorhinal cortex is the main gateway between the hippocampal formation and theneocortex. The entorhinal cortex mainly projects to the hippocampal formation via layers IIand III. While the various functions of entorhinal cortex layer II has been extensively studiedin recent years, the connectivity of entorhinal cortex layer III has remained relativelyunstudied. Here we seek to take advantage of novel transgenic tools and viral tracers in orderto trace the up‐ and downstream connections of layer III in the medial entorhinal cortex. Thecombination of methods we use enable us to target a group of cells with unprecedentedspecificity, allowing accurate identification of local and global projections.Previous work has shown that layer III of the entorhinal cortex projects to CA1 and thesubiculum, both ipsilaterally and contralaterally, while the main inputs to layer III are thepresubiculum, postrhinal cortex and layer V of the entorhinal cortex. Using cell type specifictracing methods, I find largely similar afferent and efferent connections, but for the first timewith layer specificity in mice. I also find that a recently described input from CA2 to layer II ofthe medial entorhinal cortex could also project to layer III. Additionally, I find support for themore recently described parasubicular input to layer III of the medial entorhinal cortex. Finally,these data show a larger input to MEC LIII from the CA1 than what was expected fromtraditional tracing methods. These novel findings may be the result of technical artifacts,species differences or previously under‐reported connections. Overall, this thesis shows thestructural connectivity to and from MEC LIII in the mouse, and could lead to future functionalconnectivity studies in the area.