For the last two decades, in one of the city center districts of Istanbul, called Beyoglu (pera), there has an inverse proportion between the crime factor and the population been observed. The subject of the paper is to compare the crime factor and the urban quality parameters of two historically and physically similar quarters of Beyoglu. The analytical discussion of the parameters mentioned above , is based on the triple case studies such as built environnement anlyses, socio cultural profile analyses and the criminal files analyses. The results of the prove that there is an interactive relationship between crime factor and environnemental quality.