In Chile, as in many South American countries, AASHTO-93 is the current official method for the design of asphalt pavements.The method gives an estimated number of 80 kN standard axle loads (W 18 ) that the pavement can withstand for a certain serviceability.A safety factor is then applied to W 18 to take into account the confidence level and the estimated variance of the inputs used in the method, whereby the magnitude of the structure's life cycle is estimated.Normally, data used in the AASHTO-93 method are assumed to be deterministic, disregarding their random nature.This paper presents a probabilistic assessment of the AASHTO-93 pavement design method under Chilean conditions, which provides a set of probability density functions (PDFs) that allow a probabilistic estimation of the pavement life cycle in terms of the value W 18 .To achieve the goal, we developed a simulation model based on a sample of 13 groups of roads located throughout Chile.