A simplified method for the assessment of the reactivation potential of narrow mudslides is proposed. The method uses the factor of safety, calculated by 2D limit equilibrium method, but incorporating an additional strength component due to the friction in the lateral margins of the mudslide. The method was applied to three mudslides in the eastern Pyrenees. The location of the sliding surface was estimated from transversal cross-sections, and the safety factor was calculated using the residual strength and hypothesizing the depth of water table in the mudslide body. The results show that the lateral component of the strength is crucial and that the three mudslides probably will reactivate in the future. The technique was checked by comparing the safety factors calculated with the frequency of past reactivations, which was obtained independently by dendrochronological dating. The lower the values of safety factor of the mudslides, the higher the frequency of reactivation, as it was expected.