Creep tests were conducted on directionally solidified TiAl-Si alloys to discern the effect of the lamellar orientation and the addition of silicon on the high temperature strength. Growth from a seed by the floating zone technique was used to align the lamellar microstructure for ingots containing 3 at. % Si. The as-processed material consisted of a PST like matrix containing large eutectic silicide particles within the interdendritic spaces and small silicide precipitates along the a,ly lamellar boundaries. In addition, ingots with large columnar grains of various lamellar orientations were also produced by the floating zone technique. Texture measurements by X-ray diffraction were used to identify the lamellar orientation. Tensile creep tests were conducted on both sets of ingots. The results show the beneficial effect of microstructural control to align the lamellar boundaries parallel to the loading axis. The addition of Si is also effective to improve the creep resistance.