The pressure dependence of the quality factors of several lateral microelectromechanical resonators is measured, by exploiting an electrical, non-linear second harmonic method that eliminates the effect of capacitive parasitics without requiring additional driving and/or frequency conversions. Analytical models for the possible causes of energy loss due to the residual gas surrounding the resonators, namely slide-film and squeeze-film losses, are compared with the experimental data. (C) 2004 Elsevier B.V. All rights reserved.