This study aims to develop a better understanding of diffusion of Geographic Information Systems within municipalities and examines the infrastructure of Istanbul municipalities and whether they are ready for this technology or not. This study uses two research methods: The first one comprises interviews with the experts of GIS in Turkey. The second one comprises questionnaires conducted with Geographic Information Systems - related departments of Istanbul municipalities. Data collected online have been analyzed by using descriptive statistics, reliability tests, Anova and regression to test the hypotheses. One of the findings is that almost half of the municipalities implement Geographic Information Systems without a vision or a plan for the future. Another finding is that Geographic Information Systems is mainly used to perform registration and maintenance functions instead of supporting the decision-making process. Finally, there is an optimistic expectation of municipalities regarding the use of Geographic Information Systems in the future.