Abstract : This paper focuses on the study of fibrosis induced by an implanted medical device and explores the possibility of characterizing this process by in situ measurement of electrical impedance. The approach combines concurrent electrical and biological characterizations of fibrotic tissue, applied to electrodes implanted in an animal model. The methodology used is described. Initial results evidence the strong correlation between fibrotic tissue and electrical parameters. Identification of such electrical parameters will enable the establishment of a reliable monitoring method.