Dyeing of textiles with natural dye was started in the early stage by the traditional dyers. In this century, a global awareness is already in place favoring the use of natural resources for protecting the environment and earth from pollution and ecological imbalances. In this study fully, environmental friendly dyeing of wool fabric was investigated using natural dye and natural mordant extracted from Cassia singueana plant and mango bark respectively. Wool fabric was dyed with Cassia singueana extract using different combinations of dyeing temperature, time, pH and concentration of extracted dye solution. Color strength, CIE L* a* b* and fastness properties (washing, rubbing and light), were investigated. The fastness property results of all dyed wool fabric samples with Cassia singueana plant extract were in the range of Good to excellent.