For the first time, an in-situ degradation monitoring system for biodegradable polymers is reported in present work. The proposed concept is based on a conductive biodegradable polymer composite, where carbon nanotubes (CNTs) are incorporated in poly(lactic acid) (PLA) in order to develop an intelligent biocomposite system that can sense biodegradation. Changes in electrical resistivity of the PLA/CNT nanocomposites were successfully correlated with degradation levels of the biopolymer. PLA/CNT nanocomposites demonstrated excellent degradation sensing abilities at CNT concentrations around the percolation threshold, with resistivity changes of about four orders of magnitude with biodegradation. In contrast to many other stimuli, biodegradation resulted in a reduction in resistivity due to an increased CNT network density after partial removal of the amorphous phase of the polymer matrix. (C) 2013 Elsevier Ltd. All rights reserved.