The effect of sand grain shape and size on the mechanical behavior of geotextile-reinforced sands is investigated in the present research, based on the results of triaxial compression tests. Six clean uniform sands differing in grain shape (subangular or rounded grains) and/or grain size as well as one non-woven and three woven geotextiles with or without apertures, were used in this experimental investigation. Triaxial compression tests were conducted on specimens with a diameter of 70 mm and a height of 144 mm, consisting of dry and dense sands reinforced with 3, 5 and 7 horizontal geotextile disks. The geotextile-reinforced sands present higher strength and axial strain at failure than the unreinforced sands. The strength of reinforced sands increases with decreasing sand grain size, with increasing number of geotextile layers and is affected by the grain shape of sand, since it was observed that reinforced sands with subangular grains attain higher strength values than the reinforced sands with rounded grains. The triaxial compression tests yielded bilinear failure envelopes for all geotextile-reinforced sands.