The performance of modern MOSFETs is limited by the presence of parasitic series resistances and mobility degradation. This article reviews and assesses 18 of the extraction methods currently used to determine the values of parasitic series resistances and mobility degradation from the measured drain current. The methods are separated in 3 groups: seven different methods that use the transfer characteristics of several devices having different mask channel lengths; five methods based on a single device with different drain and gate bias; six methods which account for the asymmetry between drain and source resistance.