This study was conducted to determine the effects of plant extract mixture (PEM) inclusion at different levels and copper into diets of hens on performance, egg quality traits, yolk and serum cholesterol content and yolk fatty acid composition. A total of 192 Lohmann white layers, 38 wks of age, were used in this study. The experiment was carried out on a control and 7 treatments groups (basal diet plus 200 mg/kg copper (CuSO4 center dot 5H(2)O), 500 mg/kg PEM, 500 mg/kg PEM + 200 mg/kg copper, 750 mg/kg PEM, 750 mg/kg PEM + 200 mg/kg copper, 1000 mg/kg PEM + 200 mg/kg copper). PEM, copper and PEM plus copper combinations did not affect performance parameters. Increasing level of PEM increased quadratically shell stiffness and linearly shell thickness, but did not affect other egg traits. Treatments had no a significant effect on cholesterol and trigliserid concentrations of egg and serum. While supplemented PEM and copper did not affect fatty acid level of yolk, PEM plus copper combination increased oleic acid and total MUFA levels. Results obtained from present study showed that supplementation of a mixed herbal product containing Origanum vulgare (dried leaf), Thymus vulgaris (dried leaf), thyme oil, origanum oil, garlic oil, anise oil and fennel oil to diets of laying hens can be beneficial to improve egg quality traits especially such as shell stiffness and thickness.