We fabricated a new series of transparent ceramics based on (1x)LaAlO3xSr(Al0.5Ta0.5)O3 solid solution. These transparent ceramics were obtained by a conventional solid-state reaction, and the crystal structure and its optical properties were investigated. The X-ray diffraction (XRD) analyses of the ceramics revealed a cubic perovskite structure with a higher Sr(Al0.5Ta0.5)O3 content (Pm-3m for x=0.40.6 and Fm-3m for x=0.71.0), whereas the ceramics contained rhombohedral perovskite phase at x=0.00.3. However, the Raman scattering study revealed that an Fm-3m ordered structure was contained above x=0.2. High transmittance was obtained at the cubic composition (x=0.41.0), and was particularly high at x=0.50.7. It was demonstrated that these transparent ceramics had both a high refractive index and a high Abbe number (low dispersion). The Abbe number of the x=0.5 composition, 37.8, was higher than that of Ba(Mg,Ta)O3 system transparent ceramics (30).