In recent years, the use of low-environ mental impact biotechnology giving rises to new types of treatment in the textile industry. The use of protease enzymes to improve some physical and mechanical properties such as smoothness, drapeability, dyeing affinity and water absorbency is particularly interesting. In this research, wool yams were first treated with different concentrations of protease enzymes in water solution including 1, 2, 4 and 6% o.w.f. for 60 min. The dyeing process was then carried out on the treated yams with madder (50% o.w.f.). Tensile strength of treated yams was decreased due to enzyme treatment and it continued to decrease with an increase in enzyme concentration in solution. The L* values decreased for the samples treated with enzyme. The wash and light fastness properties of samples were measured according to ISO 105-CO5 and Daylight ISO 105-1301. ne washing fastness properties of treated samples were not changed. In the case of light fastness properties, it was increased a little for 4% and 6% enzyme treated samples. (c) 2006 Elsevier Inc. All rights reserved.