A patient interface includes a frame having a circular opening to receive pressurized gas and a cushion supported on the frame and defining a breathing chamber configured to receive the pressurized gas. The patient interface further includes support structure configured to support the patient interface on the patient's head, a plurality of gas washout holes configured to vent gas from the breathing chamber to atmosphere, and an elbow assembly. The elbow assembly includes a rotatable elbow that is releasably snap-fittable to the frame. The rotatable elbow having a pair of diametrically opposed flexible sides that are configured to flex upon engagement with the frame and produce an audible click when the rotatable elbow has been securely attached to the frame. The rotatable elbow further includes a pair of diametrically opposed finger depressable release portions that are resiliently movable towards one another to allow release of the rotatable elbow from the frame.