A balloon inflator for simultaneously filling two balloons to substantially identical sizes includes an air pump having a first air chamber communicating with a first inflation nozzle and second air chamber communicating with a second inflation nozzle. A reciprocating piston causes an alternating increase and decrease in the first and second air chambers to advance air to fill balloons on the first and second inflation nozzles. The volume of inflation gas advanced to the first balloon inflation nozzle is substantially identical to the volume of inflation gas advanced to the second balloon inflation nozzle, thus permitting a virtually identical inflation of a first balloon at said first balloon inflation nozzle and a second balloon at said second balloon inflation nozzle upon repeated reciprocation of the piston.