High-resolution multi-band spectrum occupancy measurements and evaluations at 900MHz downlink band for Istanbul metropolitan Radio frequency spectrum is one of the most important resources for both contemporary and next generation wireless communications (NGWC) systems. Therefore, utilization of the radio frequency spectrum is a critical task. Reliable occupancy statistics are key to such utilization. Considering the fact that Turkey will migrate to digital terrestrial TV broadcast in the near future, a specific portion of the radio frequency spectrum will be available. Hence, occupancy statistics and relevant analyses are mandatory for both contemporary and NGWC systems. Results of high-resolution multi-band spectrum occupancy measurements at 900MHz downlink band for Istanbul metropolitan are presented. Two of the prominent evaluation methods and corresponding occupancy statistics are given in a comparative manner. It is observed that parameters of the evaluation methods affect the occupancy statistics drastically.