Most of synthetic dyes are toxic for the environment. On the other hand, natural dyes are ecofriendly and can replace synthetic toxic dyes. In the present studies, a natural dye was extracted from rinsed and grinded olive peel in 1:10 ratio (m/V) with water. Then, fabrics (wool and silk) were dyed with the peel extract by using different types of dulling and shining mordants (FeSO₄, CuSO₄, CoSO₄, SnCl₂, K₂SO₄, Al₂(SO₄)₃, ZnSO₄ and NiSO₄). The mordants have shown best results for wool at the acidic pH (4-5) and for silk at the basic pH (8-9). After dyeing wool (at 70-80ºC) and silk (at 100ºC) with olive peel extract, by simultaneous mordanting method, an interesting variety of beige, buff and khaki shades were obtained. Color fastness was noted by matching the dyed fabric color with grey scale. The colors of dyed fabric were again noted after its washing, pressing by iron, rubbing and light exposure. The fastness results were found quite satisfactory. The investigated procedure of natural dye extraction is eco-friendly, safe for the environment and a safe technique as it does not involve any organic solvent. The natural dyes can be satisfactory potential substitutes of the synthetic environmentally hazardous dyes.