Abstract: A parenteral liquid administration set is provided which comprises flexible tubing, connection means with a parenteral liquid source at one end of the tubing, and means for connection to a blood vessel-penetrating member, such as a needle, at the other end of the tubing. In accordance with this invention, a filter, positioned in fluid communication with the bore of the tubing, comprises a housing, which carries first and second filter members in parallel flow position so that each increment of fluid flow through the tubing passes through one or the other of the filter members. The first filter member is hydrophilic, to permit the passage of solution under normal administration conditions. The second filter member is hydrophobic, to permit the passage of gas after wetting of the filter members. Accordingly, the filter members, which are closed from the exterior by the administration set, cannot airblock by the accumulation of air bubbles immediately upstream of the filter members.