Oscillating pressure inflations may minimize trauma to the coronary artery during coronary angioplasty. We measured in vitro diameters of polyolepin copolymer compliant angioplasty balloons (as a surrogate for pressure) during pressure oscillation at the inflator to determine if pressure oscillations at the inflator were conducted to the balloon. Balloon diameter oscillation increased as cycle length and inflator pressure amplitude increased. Currently practiced oscillating inflation (cycle length 2-3 sec, amplitude 2-3 atm) did not effectively transmit oscillation to the balloon. Clinically feasible optimal balloon oscillation was achieved at a cycle length of 6 sec and pressure amplitude of about 3 atm.