In this study was evaluated the effects of rosemary (Rosmarinus officinalis) essential oil on performance and eggshell quality parameters of laying hens. In experiment, a total of 192 twenty four-week-old NOVOgen White laying hens were assigned to the basal control diet supplemented with 50, 100, 150, 200 and 250 mg/kg of rosemary essential oil (6 treatment diets, 8 replicates, each replicate consists of 4 hens). Hens were fed with experimental diets from 24 to 36 weeks of age. Water and feed were supplied ad libitum throughout the experiment. The results of study indicated that there were no differences in egg production, feed intake, feed conversion ratio, egg weight, egg mass as performance parameters among the treatment groups. The eggshell weight had no significantly affected by the dietary treatments. However, eggshell thickness and eggshell breaking strength were significantly affected by the treatments (P< 0.05). The eggshell thickness was significantly increased fed with 250 mg/kg rosemary essential oil supplemented of group when compared to the control group. The breaking strength was increased by the addition of dietary rosemary essential oil. The results of this study demonstrated that performance parameters were not significantly influenced with rosemary oil addition in laying hens diet. But, rosemary oil addition in laying hens diet significantly increased to eggshell breaking strength. It may be said that the dietary addition of 50 mg/kg of rosemary essential oil would be beneficial to improve the egg shell quality in laying hens.