Free and esterified forms of provitamin D in 30-day-old mele rat skin were isolated and quantitated using silicic acid column chromatography and high-performance liquid chromatography(HPLC) systems. Two forms of free provitamin D(cholesta-5, 7-dien-$3{eta}$-ol and cholesta-5, 7, 24-trien-$3{eta}$-ol) and at least thirteen esterified forms of provitamin D were isolated. The average total concentration of provitamin D in the whole skin was $6,056ng/cm^2$. The skin contained $846ng/cm^2$ of free provitamin D and $5,209ng/cm^2$ of esterified provitamin D. The proportion of esterified provitamin D in the skin was 86%.