The starch of three Andean tubers have been studied (Oxalis tuberosa, Ullucus tuberosus, Tropaeolum tuberosum). Qualitative optical methods, scanning electron microscopy and quantitative analytical microscopy have been used. Statistical tests have been applied to the results. The comparative study of starch grains morphology provides important characters for their identification. As a result, starch would be an element of high value in the determination of material recovered from archaeological sites in different preservation conditions or used in food elaboration.