The structural parameters of orthorhombic and tetragonal phases (space group Plmmm and p4/mmm) of A-site deficient La-0.683(Ti0.95Al0.05)O-3 pervoskite have been refined by Rietveld analysis through the X-ray powder diffraction patterns measured in the temperature range from 15 degrees to 500 degreesC. With an increase in temperature the unit-cell parameters a, b, and c increased, while the b/a ratio decreased and became unity between 200 degrees and 400 degreesC. No significant changes were observed for atomic coordinates throughout the temperature studied. These results strongly suggest that the phase transition is induced by lattice distortion.