The mosque is considered one of the most important religious buildings for Muslims, it is the place of performing religious rituals, It's also playing an important religious and societal role and therefore it has a great importance to the individuals and Muslim society. The design of the mosques carries a number of vocabulary and distinctive architectural elements such as minarets, domes, Mihrab, Minbar and internal courtyard (Sahn). It contains some of the vocabulary associated with some of religious symbols and also, in some cases, some religious and social activities and uses may be joined with the mosque. The research problem is the lack of interest in achieving the sustainability requirements in some mosques, which leads to increase the energy consumption ,increase water consumption, increase the consumption of resources and increasing the operation cost. Achieving sustainability in buildings is an important trend in the current period locally and internationally. Because the mosque is an important building to Muslims, therefore, it is necessary to work towards achieving sustainability in the mosques. The research seeks to establish the concept of sustainable mosques by trying to achieve the principles of sustainability in the design of new mosques and the existing mosques, the research has made a theoretical study followed by an analytical study of a number of case studies of mosques from several countries, the research has studied also some case studies of mosques that were developed to meet some requirements of sustainability. The analytical study included of the most important international experiences to achieve the aspects of sustainability in the design of mosques and in the existing mosques, which led to conclude the latest international solutions and methods in this field, to identify the architectural elements of the mosque that can be utilized for the purposes of sustainability, and to extract the most important aspects, with the utilizing of the latest ideas, to reach the appropriate and applicable solutions to support the sustainability requirements. The research aims at providing an approach to support the sustainability requirements in the design of mosques and in the existing mosques. The research has concluded this approach to aid to support achieving sustainability in the design of new mosques, and improving the performance of existing mosques towards sustainability, including the required treatments and solutions, the utilizing of the architectural elements of the mosque to support achieving the sustainability, utilizing of the modern technological developments and the recent international ideas.