Istanbul, as one of the most significant coastal cities of Turkey, has very unique cultural, historical, ecological and social dynamics. As the economic centre of the country, the city has been exposed to human attraction throughout centuries. However, in recent decades Istanbul has been experiencing rapid growths in population; this has instigated dramatic changes regarding the urban patterns, as well as the coastline of the city. Although some legal regulations had been arranged as a precaution to protect the uniqueness of the city's coastal areas, these efforts of conserving the coastline have been overruled by unforeseen planning actions, which resulted in more deformation in the last decades. In this paper, we aim to determine the coastline changes in Istanbul between 1852 and 2011 and unravel their correlation with the legal regulations implemented. As evidence for this argument, we will utilise historical maps and aerial photographs, these resources will be assessed with GIS overlapping technique to identify the differences in coastal lines. The coastlines in these zones have been grouped as 'natural, deformed or artificial' according to its physical characteristics. As a result, visuals are compared to show the change in the coastline's characteristics, and the relation of these changes to regulations will be discussed in each analysed year. The findings are expected to be used for further research on the assessment of lost or degraded change in coastal lines between 1852 and 2011.