The application of different mechanical extraction ventilation systems in reducing and controlling dust concentrations in weaned and finishing pig houses was analyzed and discussed in this work. Dust concentrations and airflow velocities have been measured at 20 measuring points, smoothly positioned over the house cross section, in the net consisting of 4 horizontal and 5 vertical rows. The lowest horizontal row was positioned at the pigs breathing zone (40 cm above the floor), and the highest (fourth) horizontal row was positioned at the workers breathing zone (160 cm). Control values were measured in houses with closed doors and windows and all the fans switched off. These values were compared with three experimental sets of values achieved with: floor, roof and both ventilation systems. Dust concentrations were measured by konimeter (Konimeter 10, Karl Zeiss Jena), airflow velocity in ventilation ducts with a turbine anemometer and the airflow velocity at measuring points with hot wire anemometer. In the finishing house significant decrement of inhalable (F = 44.35, P << 0.01) and respirable (F = 43.82, P << 0.01) dust concentration was achieved in the third experimental treatment. In the weaned piglets house, significant decrement of inhalable (F = 49.43, P << 0.01) and respirable (F = 42.69, P << 0.01) dust concentration was achieved with floor ventilation.