The aim of this study was to review papers about odor emissions from livestock production published between 1997 and 2013. The study concerned three animal species: poultry, swine, and dairy cattle. The results of the research are presented in different units, making it difficult to compare them. For this purpose, the odor emission factors were converted with respect to 1 LU (livestock unit=500 kg). The calculated mean odor emission factor was greatest for poultry, followed by swine and dairy cattle, but the coefficient of variation for all animal species was high. Such a variability could be caused by weather and microclimate conditions, the housing system, and measurement methods. Therefore, it is reasonable to continue the odor emission research in order to precisely determine the values of odor emission factors. It is also necessary to develop the common unified methods for air sample collecting as well as unified unit of odor emission factor to make odor emission factors more comaparable. It may be useful in establishing any legal regulations on this subject.