Most of the meat industry by-products are discarded without being used as a protein resources. They often cause the pollution problems. And only a small parts of them are utilized, and handled unsanitarily as a human food. In order to develop a protein resources from meat industry by-products, optimum conditions for protein recovery from swine liver, lung and bone were examined. The results obtained were summarized as follows: 1. Amounts of extracted protein from the swine liver and lung were increased as the extraction pH was increased. But the optimum pH for extraction and precipitation were considered as 10 and 4.5, respectively in view of the collagen contents of the precipitated protein. 2. More protein were extracted from the swine bone at an alkaline pH than at an acidic pH and the extractability of the protein was increased by the addition of EDTA over all pH range. Extractability of protein was increased as the extraction temperature elevated and was decreased by the addition of KCl and NaCl when alkaline extraction method was used. 3. When water and high pressure extraction (WHPE) method was used, the extraction time for more than 4 hours at a 15 psi has no effect on the increasing the extractability of protein from bone but 3 times more proteins were extracted than atmospheric pressure was used.