In accordance with the idea that the degradation of the SiO2 network and the dielectric breakdown are intimately related, a new model to describe the breakdown statistics of thin SiO2 films is presented. The obtained distribution of failures has been found to provide very good fits of the experimental statistical data that correspond to both constant-current and constant-voltage stress experiments. The fundamental properties of the extreme-value distributions are preserved by the presented model and, what is more important, the two involved statistical parameters have a natural physical interpretation. Finally, the Monte Carlo method has been applied to simulate the degradation of the SiO2 film until breakdown, and this has been demonstrated to be a powerful technique for introducing second-order effects into the study of the breakdown statistics. © 1990.