This study presents the ACH for ten apartments in naturally ventilated multifamily dwellings for two cases inlet vent manipulations: i) fully opened inlet vents; and ii) fully closed and taped inlet vents. Even with fully opened inlet vents the resulting ventilation is rather poor. The average ACH is 0.26±0.16 h-1. All apartments fall in the lower quartile in terms of ACH when compared to other multifamily dwellings in Sweden. A method using two different tracers A and B is presented that allow for measurement of the partial flow from the stairway zone and the partial flow from other pathways into the apartment. On the average 10-20% of the airflow into a typical apartment in a naturally ventilated multifamily dwelling seems to originate from the stairway zone when the inlet vents are fully opened. By closing and taping the inlet vents, the airtightness of the apartments have been investigated. The average direct leakage flow, i.e. not from the stairway zone, is 17 m3/h but the variation is large. Layout B seems to leak the most, followed by A and then C.