This research work involves the dyeing of wool yarns with saffron petals as a source for green color. At first step woolen pile yarns treated with four different mordents, namely: tin chloride, copper sulfate, aluminum sulfate and iron(II) sulfate in acidic condition using acetic, oxalic, citric and lactic acids respectively. In this study the possibility of using saffron petals as a natural dye for wool yarn was investigated. By using different mordents a range of hues from green to yellow and brown was obtained. Color parameters, washing fastness, rubbing fastness (wet & dry) and light fastnesses of the dyed yarns were measured. It can be concluded that the best mordents for dyeing wool yarn with saffron petal to obtain green color are tin chloride and aluminum sulfate. The results of fastness tests of samples treated with tin chloride are poorer so that the best suggested mordent for dyeing wool with saffron to get green color is aluminum sulfate.