This study investigates the viability and cost effectiveness of natural ventilation in Istanbul. A typical high-rise office building was used for the investigation together with detailed local weather data including average temperature, wind speed and wind directions for each month of an average year. Data and methods provided by ASHRAE is used to calculate the air pressure at a particular window taking into account wind speed and direction, outside temperature, height and the building's location. The study uses a simple computer program to do this. Received air volume is calculated by equating useful air pressure to the pressure loss in the duct system,. The results show that a 4x0.4 m2 opening with a simple duct system at each floor, provides fresh air demand of this office building for 79.1% of the year.