Reinforced concrete frame (RCF) buildings are widely used around the world and they are present in most urban areas. This situation has occurred because they are cost-efficient, have good seismic performance and because the materials and technologies required for their construction are available in many countries. One of the decisions during the design stage of new buildings based on this structural system is selecting the type of partitions. So far, in most developing countries the use of masonry brick walls to separate habitational spaces is still the predominant choice for most new projects. This situation stems from the fact that the selection of partition elements is often motivated by architectural, economic and cultural reasons, and because there is lack of information about the potential impact of the weight of partition elements on the seismic performance. This paper presents the evaluation of the effect of the partition weight on the seismic performance of RCF buildings. For this purpose, a six-story building was designed considering three different types of partitions: a) drywall, b) expanded-reinforced polystyrene and c) traditional clay partitions. Each building design was modelled in three-dimensions using fiber elements and subjected to nonlinear analyses. Based on these results, fragility curves were calculated for different seismic performance levels. The results of these evaluations show that seismic performance improves when lighter partitions are used, particularly in the nonlinear range. These buildings showed higher performance at the life-safety and collapse levels. All things considered, the results of this research show that the weight of partitions has a notable impact in seismic performance, and it suggests that it should be given careful consideration to its choice during the design phase of a project, and that cities planners should promote the use of lightweight partitions for new buildings.