The objective of this paper is to provide an empirical analysis of the influence of traffic noise has on the housing market. Traffic noise can be considered as an environmental externality from road transport system. As so, it affects the value that people are willing to pay for their houses. The value of this effect has already been studied by some authors, with Stated Preference-choice (SP-choice) methods, the hedonic pricing model, or others. The approach used in this study combines traditional methods, namely linear modelling techniques used for quantifying the effect on housing prices fluctuation, with newer methods as the spatial analysis associate d to Geographical Information Systems. There are obvious advantages to a GIS in adding spatial analytical capabilities in terms of increasing its functionality and meeting a demand for systems that do something beyond storing, retrieving and displaying large amounts of information. This study was developed for the city of Lisbon, Portugal. A geographical database was created combining information from the Census, on the housing characteristics, with renting and sales activities. This study applies spatial auto-correlation techniques to analyze the relation between traffic noise and the variation on the housing value in Lisbon, and aims to contribute to the scientific knowledge of housing market in Lisbon, with detailed and accurate information on the factors affecting its variation.