Bursa, the first capital of the Ottoman Empire, is one of the rare historical cities that has survived to the present day without losing its importance. As well as monumental structures such as mosques and Sultan complexes, traditional Bursa houses are also components of architectural heritage that reflect the identity of the city. The traditional building materials of these houses are wood, stone, brick and earth. Today, these materials are known as ecological building materials and their use is very important to ensure sustainability. Especially the application of traditional building techniques based on the use of these materials in restoration works is of great importance in terms of ensuring sustainability not only from an ecological point of view, but also from economic and cultural points of view. In this context, earthen building material consisting of natural raw materials and created by human hands are seen as ecological and renewable building materials. In different parts of the world, many civilizations have used earthen building materials with different usage techniques in the past. This material has not lost its importance to this day. In this study, the earthen building materials used in traditional Bursa houses are examined and their role in sustainable architecture is pointed out. For this purpose, a case study was conducted on traditional Bursa houses in three different historic neighborhoods; Hisar, Tuzpazari and Reyhan regions. Representative earthen building materials were taken from 22 traditional houses and listed with their qualities for experimental studies. Characterization tests were carried out on the samples taken from these houses. The results of the experiments have been used to develop some. recommendations for the successful implementation of restorations that will help to carry out sustainable heritage conservation work in Bursa.