The present study was conducted to investigate the effect of active metabolite of vitamin D (1, 25-dihydroxy cholecalciferol or calcitriol) in comparison with vitamin D 3 on performance, egg quality and ileal nutrient digestibility of aged-laying hens. A total of 150 Hy-line W-36 laying hens of 92 wk of age were used in a completely randomized design with 5 replicates of 5 birds each. Dietary treatments consisted of the 3 levels of vitamin D 3 (50, 62.5, and 75 ?g/kg of diet) and 3 different calcitriol levels (5, 10, and 15 ?g/kg), which fed to the birds during a 77 d feeding period including 7 d for adaptation and 70 d as main recording period. Results showed that during the first 35 d period, increasing dietary vitamin D 3 and calcitriol to 62.5 and 10 ?g/kg of diet, respectively, caused significant increases (P 0.05) in egg production. Also, these levels tended (P=0.0507) to improve egg mass. However, in the second 35 d period, the moderate levels of vitamin D 3 and calcitriol improved egg production, egg mass (P 0.01) and feed conversion efficiency (P 0.05). Among egg quality indexes, only eggshell thickness (P 0.05) and shell breaking strength (P 0.01) were improved by vitamin D level in the first trial period. The vitamin source and level hadn't significant effect on antibody production titer against Newcastle disease virus during both 6 and 12 days post vaccine inoculation. Hens fed on calcitriol-diets had greater quantities of ash and Ca in their eggshell compared with vitamin D 3 counterparts. However, eggshell P content wasn't influenced by the level or source of vitamin D. Furthermore, dietary calcitriol supplementation resulted in significant (P 0.05) increase in tibial ash and tended to increase tibial Ca (P=0.0789) and P (P=0.0863). Serum mineral analysis showed that source of vitamin D had a considerable (P 0.01) impact on serum calcium and zinc concentrations so that, birds on calcitriol diets had higher levels of theses two elements in their serum. Although ileal digestibilities of crude protein and P weren't affected by dietary treatments, source and level of vitamin D had significant impact on Ca and total ash digestibilities. The highest digestibility coefficients were achieved by using 62.5 and 10 ?g/kg vitamin D 3 and calcitriol, respectively. The present findings indicate that supplementation of 10 ?g/kg calcitriol into the aged-laying hen's diets in addition to maintaining laying performance, could improves both eggshell thickness and strength. Keywords: Laying hen, Vitamin D 3 , Calcitriol, Performance, Eggshell Quality, Ileal Digestibility