The transverse piezoelectric properties of (1-x)Pb(Yb1/2Nb1/2)O-3-xPbTiO(3) (PYbN-PT, x = 0.5) epitaxial films grown on (0 0 1)SrRuO3/(0 0 1)LaAlO3 (indices given for the pseudocubic unit cell) were investigated by the wafer flexure technique. PYbN-PT films and SrRuO3 bottom electrodes were deposited by pulsed laser deposition. At a deposition pressure of 400 mTorr, (0 0 1) PYbN-PT epitaxial films with high phase purity and good crystalline quality were obtained for a wide range of deposition rates (40-100 nm/min) and temperatures (620-660 degreesC). The remanent polarization of the film was as high as 30 muC/cm(2). The esl coefficient and the aging rate were strongly dependent on the poling direction. The maximum esl coefficient was -11.0 C/m(2). The minimum aging rate of the piezoelectric coefficients for the films was 2% per decade.