Diffusion of Fe-59 in single crystalline gamma-TiAl intermetallic compound has been investigated by the ion-beam sputter-sectioning technique in the temperature range from 1123 to 1303 K. The diffusion coefficients measured in the directions parallel (D-33) and perpendicular (D-11) to the [001] axis exhibit significant anisotropy; the diffusion of Fe-59 parallel to the [001] direction is faster than that perpendicular to the [001] direction. The activation energy for diffusion of Fe-59 parallel to the [001] direction is smaller than that perpendicular to that direction. The anisotropy of Fe-59 diffusion was opposite to that of Ti-44 self-diffusion. It is suggested that this anisotropy is related to site occupation of Fe in TiAl and the jumps of atoms through vacancy jumps. (C) 2003 Elsevier Science B.V. All rights reserved.