Clothing and textile materials are not only the carriers of microorganisms such as pathogenic bacteria, odor generating bacteria, and mold fungi, but also good media for growth of the microorganisms. These microorganisms, if pathogenic or infectious, may cause problems to wearers or users of the textile materials. Hence it becomes very important to finish garments with special chemicals that can restrict the growth of these microorganisms. Nevertheless, inappropriate antimicrobial finishes have some shortcomings such as unsatisfactory wash fastness, lack of durability, and either too strong or too less antimicrobial action.Taking these factors into consideration, in this study an attempt has been made to discuss the effects of the microorganisms on textile products, the kinds of antimicrobial finishes and agents, the evaluation systems of antimicrobial activity. The analysis should be helpful to professionals in identifying the best possible method to put antimicrobial activity on PET fibers.