Ten natural dye yielding and two mordant plants were biochemically analyzed. Though natural dyes are widely used, information about the active principles responsible for dyeing is hardly available. In the present experiment, total chlorophyll, carotinoids, tannins, phenolics, flavonoids and curcumin were determined among the dye yielding plants, while K, S, P, Ca, Mg, Mn, Zn, Fe, Cu and Co were determined in the case of mordant plants. In Bixa orellana, used for yellow dyeing, the carotinoid content was 163.11 mg g -1 and in Clerodendrum chinense and Datura stramonium, which were used for green colouring, total chlorophyll content of 10.29 mg and 11.83 mg g -1 was recorded. Curcumin content responsible for orange colouring in Curcuma domestica was 27.7 mg g -1 while flavonoid content in Solanum nigrum and Terminalia chebula, which were used for brown, brown to black dyes was 24.89 and 21.73 mg g -1 . Among the plants used for dyeing different colours, Punica granatum and Parkia timoriana were found to contain higher amounts of total phenols and bound phenols by recording 681.2 mg g -1 and 287.6 mg g -1 total phenols and 151.6 mg g -1 and 130.2mg g -1 bound phenols, while higher amounts of orthodihydric phenols and tannins were recorded in Punica granatum and Strobilanthes flaccidifolius by recording 20.11mg g -1 and 9.54mg g -1 orthodihydric phenols and 675.57mg g -1 and 648.12 mg g -1 tannins, respectively. In case of the plants used as mordant, higher contents of Ca, Mg, K, Zn, Fe and Mn were detected in Achyranthes aspera, while higher amounts of P, Fe and Cu were recorded in Garcinia xanthochymus.