In this study, effect of inlet/outlet configurations on the dispersion and removal of fine particles are examined experimentally and numerically. Ten different inlet/outlet configurations are tested for three different contaminant release cases as by incoming air, from breathing level and close to the outlet. Air velocity and contaminant distributions, air change efficiency, contaminant removal effectiveness and particle decay are investigated for each case. Results revealed that both inlet and outlet opening positions have a strong impact on the performance of the ventilation system. The highest air change efficiency is achieved for the inlet/outlet positioned on the same vertical wall. In terms of particle removal, ventilation performance changes up to the particle source position and the area of interest. The most proper inlet/outlet positions should be decided by considering the source position and the main region of concern of the ventilation system. Moreover, close relation of particle source and outlet opening is found most likely to remove the contaminants effectively.