A transmission breather assembly includes a vertically disposed stanchion or stem having a castellated end and an annular shoulder axially spaced therefrom. The stanchion defines an internal passageway which communicates with the interior of the transmission either directly or through a flexible tube. The stanchion may be secured to a surface such as the vehicle firewall or may be mounted directly to the transmission housing if space and packaging requirements permit. Disposed on and over the castellated, open end of the stanchion is a cap or cover. The cap or cover includes an internal cylindrical wall that cooperates with the castellated end of the stanchion to retain it thereon and creates an annular space adjacent the stanchion which functions as an air passageway. The lower open end of the cap or cover is generally radially aligned with the annular shoulder on the stanchion. The cap or cover is fabricated of a hydrophobic material.