The testing results for the work of 48-leaf collimator set up on the Mevatron Primus Siemens linear medical electron accelerator have been considered on evidence obtained by film dosimetry. On testing there were estimated such parameters as the gentry and the collimator attitudes relative to the zero-level, the collimator leafs positions while the gentry and the collimator were rotating, interleaf and interblock radiation leakages, wedge factors for physical and virtual wedges, radiation field dimensions. Practical recommendations on specification and periodicity of calibration procedures for clinical conditions are given.