The increased cost of energy for laying hen diets has resulted in the use of dietary enzymes such as xylanase to increase energy digestibility and reduce the need for supplemental dietary energy. A 24-wk-long experiment was conducted using 432 17 wk old Hy-Line W36 first-cycle laying hens to determine the effects of energy concentrations and xylanase supplementation (Hostazym® X100) on hen performance, metabolizable energy and body composition. Three concentrations of dietary energy fed with and without xylanase supplementation and arranged as a 3 x 2 factorial: Control (C); C-77 kcal/kg diet and C-154 kcal/kg diet were fed with and without xylanase supplementation. Egg production, feed intake, body weight, egg weight, egg mass, feed efficiency and egg solids data were collected over the 24 wk experimental period. Nitrogen corrected apparent metabolizable energy was determined at 12 and 24 wk and body composition (crude fat, crude protein and ash) was determined at 24 wk. Hens fed dietary xylanase resulted in increased hen-day egg production over wk 1-16 and 1-24 (P < 0.05). Feed intake was increased with reduced dietary energy (P < 0.05). Egg mass and feed efficiency were improved with xylanase over the experiment, but significance was only achieved at select time periods. Hen body weight, egg weight and egg solids were generally not different among treatments. Main effects at wk 12 showed that reduced energy resulted in reduced AMEn and xylanase increased AMEn. In contrast, AMEn at wk 24 resulted in reduced AMEn with xylanase treatment. There were no differences in carcass protein or ash composition, but carcass fat resulted in an interaction as xylanase increased carcass fat in the control diet but reduced it in the C-77 kcal/kg diet. Overall, supplementation of xylanse to laying hens increased egg production, egg mass and feed efficiency over the 24 wk period although AMEn and body composition data were mixed.