This research characterizes and models the mismatch of electrical parameters in advanced MOS transistors. All characterizations are made through a test structure, which is experimentally validated using a structure based on Kelvin method. A model, valid in the linear region, is proposed. It is used for modeling the threshold voltage fluctuations of the transistors with pocket-implants, for any transistor length and gate voltage. It gives a deep understanding of the mismatch, especially for devices with non-uniform channel. Another study analyzes the mismatch of the drain current by characterizing and modeling in terms of the drain voltage. A second model is then proposed for transistors without pocket-implants. In order to apply this model, the correlation of threshold voltage fluctuations and mobility fluctuations must be considered. Characterizations are also performed on transistors with pocket-implants, showing a new drain current mismatch behavior for long transistors. Finally, characterizations are made to analyze the impact of gate roughness fluctuations on mismatch.