The nucleic acid bases play obviously important roles in biology. Understanding their electronic structure gives insight into their properties and function. Here, we report results of theoretical calculations on the electron momentum structure of adenine. Electron momentum spectroscopy (EMS) is a unique experimental technique as it gives an alternative picture of molecular electronic structure, allowing the simultaneous study of molecular orbital binding energies and momentum distributions (MDs). Quantum mechanical calculations of the electronic structure of adenine and simulations of its molecular orbital MDs will be presented. The calculations use the MP2, B3LYP and RHF levels of theory using the TZVP basis set. Representative examples of the calculated orbital MDs will be discussed along with calculated properties of the molecular electronic structure.