Hot-carrier damage is a major issue in the long-term reliability of metal–oxide–semiconductor field effect transistors (MOSFETs). Hot-carrier induced damages have been shown to degrade various MOSFET characteristics—threshold voltage, channel charge mobility, parasitic drain and source resistances, and parasitic drain capacitance. The degradation induces changes in the small-signal s parameters of MOSFETs. Further experimental results indicate that such damages also degrade the radio frequency (rf) noise characteristics of a LLD n-type MOSFET (NMOSFET). The minimum noise figure (NFmin) and the normalized noise resistance (rn)–two key noise parameters—increase due to hot-carrier stress. The optimal reflection coefficient (Γopt) versus frequency curve also changes with increase stressing. The degradation in the rf noise characteristics of the LDD NMOSFET implies a serious issue in designing reliable, low-noise rf circuits with MOSFETs.