Intelligent and multifunctional yarns (textiles) have attracted interest because of their high potential in applications such as flexible displays, batteries, or sensors. The main objective of our research was to obtain the flexible and electrically conducting yarn based on the conductive polymer and polyethylene terephtalate (PET) yarns. Among the conductive polymers, polyaniline (PANI) is considered as a promising material and is well adapted for modifications of textile structure because of its excellent environmental, thermal, and chemical stability. Chemical PANI coating on PET yarns was performed by absorption of yarns through PANI solution. The electrical, mechanical, and electro-mechanical properties of PET conductive yarns prepared were investigated. The environmental effects on the electrical and mechanical properties of the obtained conductive yarns were also studied. These conductive yarns are expected to be used as fibrous sensors, connection devices in smart clothing, and for electromagnetic shielding applications. (c) 2006 Wiley Periodicals, Inc.