The objective of this study was to evaluate the effects of different levels of Lavander stoechas essence on blood parameters and ovarian morphology of laying hens for 8 weeks. This experiment was conducted with 160 Hy-Line (W36) laying hens (30 wks of age) randomly divided into 4 experimental groups, 5 replicates and 8 birds per each (2 cages for each replicate and 4 birds in each cage). Treatments were control (without Lavander essence), and levels of 200, 400, and 600 ppm Lavander essence. All hens were provided the layer diets (2870 kcal/kg ME and 15.5 % CP) ad- libitum and received 16 h of light/ 8 h of dark. At the end of experiment, 2 birds of each replicate were randomly selected and blood samples were collected by brachial venipuncture. Serum was harvested by centrifugation and frozen for future analysis of plasma lipid. After that birds were killed by cervical dislocation for morphological assessments of ovaries. The weights of the oviduct, ovary, and stroma were recorded. The stroma weight comprised the ovarian tissue remaining after the large yellow follicles (LYF) were counted and removed. The number of small yellow follicles (SYF) and postovulatory follicles (POF) was recorded. Blood triglycerides, glucose and HDL were not affected by the treatments but by adding Lavender essence to the diet, cholesterol and LDL concentration decreased significantly in comparison with control diet (p<0.05). In addition, the levels of Lavander essence had no effect on the relative weight of the ovary, oviduct, stroma and number of SYF and POF. However, the levels of 200 and 400 ppm of Lavender caused significant increase of number and weight of LYF. The results showed that the addition of essence of Lavender up to 400 ppm increased weight and numbers of LYF
