[en] Tools for the interpretation of low-resolution electron-impact mass spectra have been developed. They may be used by the beginner in order to learn more about reactions taking place during fragmentation processes as well as by the experienced scientist to facilitate daily routine, for instance for the interpretation of a mass spectrum of an unknown compound. A computer program called MS-UTIL has been written which permits the interactive creation of fragments when starting from a given low-resolution mass spectrum and a selected chemical structure. An included editor allows to draw and edit chemical structures and to create and modify mass spectra. Fragments created can be displayed as a tree. A mathematical has been proposed which permits an easy comparison of the peak pattern of created fragments with the pattern of the mass spectrum. The program also serves as a tool for verifying fragmentation mechanisms and for checking presumptive chemical structure formulas of unidentified chemical compounds. Additionally, the occurrence of key fragments described in the literature has been quantitatively investigated. Statistical probability of the presence of defined substratures was determined for mass spectra possessing a peak at a selected mass, said peak being higher than a threshold. Principal Component Analysis has been applied to determine the major classes of substructures associated with given key fragments. All of these methods can be carried out on a PC and may serve as a means to draw conclusions about the possible structure of an unknown compound more easily when starting from the mass spectrum. (author)