In recent years there has been a great interest in the application of natural dyes in dyeing textiles due to their biodegradability and high compatibility with the environment. According to the experts, there is a great potential for using natural dyes to the extent that in some areas they can very easily replace synthetic ones. This paper reports the studies available on the characterization, classification and analysis of natural dyes; extraction of dyes from onion's outer shell and effects of different mordants and mordanting methods on the color shade. From an environmental point of view, replacing synthetic dyes with natural ones is not only a strategy to reduce risk and pollutants, but also an opportunity for new markets and jobs.