In the extensive air shower simulation program CORSIKA the interaction models HDPM and VENUS are available to simulate hadronic reactions of cosmic rays in the atmosphere. In a test version of CORSIKA we have implemented three other interaction models which are widely used in air shower simulations, namely SIBYLL, QGSJET, and DPMJET. A comparison of the interaction models with each other and with experimental data was performed for primary nuclei, nucleons, and mesons in the energy range from 1011 to 1017 eV colliding with protons and nitrogen. Some results of this comparison are presented and differences between the models with respect to their impact on the air shower development are discussed.