The Yb3+-doped YAlO3 fiber single crystals were grown by the modified micro-pulling-down method with the radiofrequency system. The starting melt compositions of (Y1-xYbx)AlO3 were varied as x = 0.05, 0.1 and 0.2. The best Yb3+-doped YAlO3 fiber single crystals were obtained for pulling-down rate equal to 0.12 mm/min. The grown fiber crystals were transparent and nearly colorless. The purpose of this study was to reveal the conditions of twin and inclusion-free growth of the Yb3+-doped YAlO3 single crystals. To investigate the homogeneity of the grown crystals, distribution coefficient of the Y and Yb ions was measured. The transmission, photo- and radioluminescence features of Yb3+-doped YAlO3 crystal were also investigated in this study. Due to very fast charge transfer luminescence of Yb3+ in near-UV-visible spectral range and higher density of Yb-rich YAlO3, such material is promising candidate for fast scintillators. (C) 2003 Elsevier B.V. All rights reserved.