The accuracy of the reliability-based designs for pavements mostly depends on the probability density functions (PDF) associated with the resilient modulus of the pavement layer. The present study attempts to find out the appropriate PDF corresponding to the base resilient modulus (Mr) of different virgin aggregates that are used in the flexible pavements. Extensive literature study has been conducted and about 120 data points were collected from various global studies performed on virgin aggregate base materials for their use in flexible pavements. Histogram and statistical analyses are performed on the dataset. An accurate PDF is then proposed from the available distributions by using percentile (P-P) and quantile (Q-Q) fit assessment plots. The proposed mean, standard deviation and coefficient of variation associated with the best PDF are further useful for developing the reliability based design optimization methods for pavements. © ASCE.