Ferroelectric Pb0.95La0.05Zr0.53Ti0.47O3 (PLZT) thin films were prepared on quartz substrates by pulsed laser deposition (PLD) technique at a deposition temperature of 750 degrees C. The crystalline structure of the film was evaluated by X-ray diffraction. The dispersion of refractive indices and optical nonlinearities of the PLZT thin films were investigated by optical transmittance and Z-scan techniques, respectively. The film exhibited strong third-order nonlinear optical effect. A nonlinear refractive index as high as 1.3 X 10(-6) esu was displayed in the PLZT thin film. These results show that PLZT ferroelectric thin films have potential applications in nonlinear optics.