Dyeing properties of silk fabric with black tea colorants were investigated in terms of dye uptakes at various dyeing conditions and the effect of mordants on color change and colorfastness. Black tea colorants showed high affinity to silk and produced brown color. Two types of adsorption isotherm were obtained; Langmuir and Freundlich equilibrium at 360 nm and 460 nm, respectively. Thus, it is considered that both of ionic and hydrogen bondings are involved in silk dyeing with black tea colorants. Dye uptake increased continuously as concentration of colorants increased. Brown color was not changed with mordant type except that Fe mordant produced dark brown color. Mordanting did not influence colorfastness of dyed silk significantly. Therefore, mordanting was not necessary in dyeing silk with black tea colorants.