Starch was isolated from the subterraneous swollen tuberous bases and nodules of Cyperus rotundus by a wet-milling process with a yield of 24.1% on a dry weight basis. The white starch was characterized in terms of granule size, specific gravity, amylose content, cold water extracts, moisture and ash contents, paste stability, clarity, viscosity at 20 degrees C, adhesive strength and line-spread at 50 degrees C. Starch noodles were prepared and the quality assessed by tensile strength and solid loss during cooking. A textile sizing solution was formulated with the starch and the tensile strength of yarns sized with the solution examined. The starch granules were large-sized and comparable to the potato types, and had an appreciable amylose content, 26.73%. Solutions of the starch showed a high pasting temperature, viscosity and adhsive strength. The C. rotundus starch noodles and the sized yarns both elicited fairly good tensile strengths, comparable to standards.