We show that current-voltage characteristics, measured on a tetracene crystal sandwiched between two gold electrodes, are in quantitative agreement with the concept of dopant-assisted charge injection across a metal-organic interface. This notion explains the wild range of carrier mobilities recently found by space-charge limited current measurements in apparently identical tetracene crystals [ de Boer , J. Appl. Phys. 95, 1196 (2004) ] and the difference between these data and the mobility measured in the time-of-flight experiments. (C) 2004 American Institute of Physics.