|The purpose of this study was to investigate the hair dyeing properties of extracts developed from the heartwood of Caesalpinia sappan with hot distilled water solution and to examine the degree of coloration from application of the resulting natural dyes to discolored artificial hair. The results were as follows: The color of the C. sappan heartwood extract was found to be influenced by pH. Higher acidity generally led to a stronger yellow tint, while higher alkalinity led to a decrease in yellow coloration and a stronger reddish tint. Dyeing with the C. sappan heartwood extract resulted in a visible redness to the artificial hair, with some variation in color according to mordancy. Thus, hair treated with KAl(SO4)2·l2H2O fixative showed a deep brown color, and hair treated with FeS04·7H2O after mordant showed a color that was similar to black to the naked eye but was actually a deep celadon green. Dyeing of artificial hair with C. sappan heartwood extract was found to vary slightly according to dyeing period and pH. Shampoo fastness following C. sappan heartwood dyeing was found to vary slightly according to the performance or nonperformance of fixative treatment and the type of fixative used.