Triple glazing windows incorporate drainage holes on glazing beads or gaskets to provide a path for condensed water from the inside to the outside. These holes are considered to be effective for draining condensed water but may decrease the air-tightness and increase the condensation risk due to the drop in surface temperature resulting from the intake of cold outside air. In this study, the related specifications and documents on the application of drainage holes and previous studies were reviewed. For the triple glazing windows with and without drainage holes, the condensation resistance and air-tightness were evaluated and compared. Condensation resistance and air-tightness were tested in accordance with KS F 2295 and KS F 2292, respectively. The results showed that the use of drainage holes did not have a significant negative impact on the condensation resistance and air-tightness.