In order to utilize skin of bullfrog (Rana catesbeiana Shaw) as an alternative source of collagen, we investigated and compared biochemical and physical properties of collagens isolated from bullfrog skin. Two kinds of collagen (BSASC; bullfrog skin acid-soluble collagen and BSPSC; bullfrog skin pepsin-solubilized collagen) were isolated by subsequent treatments with acetic acid and pepsin. The amounts of skin collagen isolated in the subsequent treatments were 7.3% BSASC and 18.2% BSPSC on the basis of lyophilized bullfrog skin weight, respectively. According to the electrophoretic pattern and CM-cellulose column chromatogram, the BSASC has the chain composition of ${alpha}1{alpha}2{alpha}3$ heterotrimer, and the BSPSC consists of two ${alpha}$ chains of ${alpha}1{alpha}2$. In addition, the denaturation temperatures of all collagens tested were ranged from $30^{circ}C;to;38^{circ}C$. This study suggests that there is a possibility to use bullfrog skin collagen as an alternative source of collagen for industrial purposes, and subsequently it may increase the economical value of the bullfrog.