In this article, arrowroot is extracted in distilled water, and its dyeing properties on wool, nylon, and silk were investigated. Also the effect of mordanting (Al, Cu, Sn, Fe and Cr compounds) on the wash fastness are measured. The wavelength of maximum absorption of the arrowroot extract appears at 250 and 300nm below pH 7, but they shifted to longer wavelength at higher pH values. It appears that the optimum condition of the dyeing of wool, nylon, and silk fabric with arrowroot extract is $60^circ{C}$, 60 min, and pH 4.0. Mordant treatments are effective in improving wash fastness of polyamide fabrics.