For many years, requirements concerning bus passenger safety have been applied following certain standards in the United States, some European Countries, South Africa etc., and this concern has become an important topic also in Latin America. Those standards are in constant evaluation along the time, each year more and more adequate with the different kinds of accidents a bus structure can suffer (frontal impact, lateral impact, rollover…) and with the new methodologies to determine the bus structural behavior in those accidents (real reduced experiments, numerical simulations…). As an attempt to improve bus passenger safety regarding accidents, earlier important efforts have been made to apply those new standards in some Latin American countries. In this context, the present paper aims mainly to look into the behavior of a bus structure in a lateral rollover, following the concepts of the standard ECE R66 [1]. This standard allows us to have a simulation of a bus rollover and thus determine the minimal structure rigidity of the bus in a rollover. To simulate a complete bus rollover the finite element method is used through the commercial software LS-DYNA [2], based on explicit time integration with large displacements and plastic deformations. The model is built with beam elements and some plastic hinges in several unions where the bus structure might have this kind of behavior during rollover. To determine the curve of those plastic hinges, experimental and theoretical predictions of the collapse of basic bus structure union elements were performed. Although the LS-DYNA [2] was used to simulate the bus structure union elements, a more complex finite element model, using shell elements, was developed in order to capture the plastic hinge behavior.