A review is given of a method for the interpretation of X-ray emission from molecules. The main part of the X-ray emission spectra is related to the singly ionized states also observable by photoelectron spectroscopy. Simplified molecular orbital calculations give in most cases satisfactory relative transition probabilities which are useful for the symmetry assignment of the states observed. High-energy structures not relating to states observed by photoelectron spectroscopy are attributed to transitions between doubly ionized states