Nowadays, urban planners are encountered with Urban sprawl in the large cities, especially in the developing countries. In order to control this condition they have taken different policies, one of these policies are increase density. The aim of this research is to determine the optimal building density in Isfahan's fifth district. To analyze this subject, firstly the selected district was divided into several quarters (neighborhoods), the indicators in each quarter were studied and weighted according to their suitability for the proposed density, then the weight of each index was established by the use of comparison matrix and eventually the suitability of each quarter was determined to propose the increase of density. The findings of the presented research indicate that because of the specific qualifications of the district, such as the existence of the valuable historic fabric of Jolfa and its neighborhood with Zayande-Rood, the historical center of the ChaharBagh-e-Bala and width of the passages and …, it`s better to avoid the increase of density in this district; and finally some suggestions is presented in order to determine an optimal density for this region.