Abstract: Background and Objective: Medicinal plants and their Essential Oils (EO) are considered safe alternatives to antibiotics in animal feeding. So, this study aimed to evaluate the effect of thyme leaves or EO on the lactation performance of Damascus goats. Materials and Methods: Thirty-six multiparous lactating Damascus goats (4 years old, an average weight 35 kg) were divided into three groups (12 animals each) after a week of parturition. Animals in the control group (C) were fed Egyptian clover (Trifolium alexandrinum) plus concentrate feed mixture without additives at the ratio of 40:60, while the other experimental animals were fed control ration plus 1% thyme leaves of total DM (G1) or the equivalent as thyme essential oil (G2). Results: Data indicated that thyme addition in form of leaves or Essential Oil (EO) significantly increased the digestibility of DM, OM and CP, decreased the digestibility of CF and fibre fractions and improved TDN and DCP values. No significant effect of sampling time or thyme supplementation was observed on rumen fermentation parameters. The highest milk and FCM yields and the lowest blood concentrations of cholesterol and triglycerides were observed with thyme addition especially leaves form (G1). Moreover, decreases in total saturated fatty acids and increases in total unsaturated fatty acids concentrations in milk were observed with thyme addition. Conclusion: It could be concluded that the supplementation of lactating goat's ration especially with thyme leaves improved the digestibility, kids growth rate and produced the highest milk yield with more healthy aspects for consumers.