Medical and economic arguments for the investigation of methods of producing blood substitutes are presented. The paper presents the current state of investigations aimed at the production of human hemoglobin from animals modified by genetic engineering methods. Certain problems related to medicine and public perception are presented in connection with the use of 'transgenic' hemoglobin as blood substitute. Swine is at present the only species among farm animals which is used in research on the production of human hemoglobin. Animals were obtained in which 'transgenic' hemoglobin accounted for 54% of the total hemoglobin in the organism. When human hemoglobin accounted for 24% of the total, and 30% was hybrid (human/swine), the animals were in perfect health, fit for reproduction and their progeny demonstrated the same transgene expression. It is assumed that human hemoglobin, extracted from the blood of transgenic swine, will be the first commercial product used in medicine and obtained through transgenesis of domestic animals.