Polluted areas are places where the level of contamination can be harmful for human health and the environment. There are about 80 000 possibly polluted areas in Sweden, 25 000 of which have been classified according to the risk of specific site. To evaluate the risk and distribution of a contamination on polluted areas, the most common way is to do a risk assessment. In addition to environmental engineering studies and surveys of the site, modelling tools can be used as a complement to try and predict the risk of polluted areas. The purpose of this study is to evaluate such a modelling tool called JAGG 2.1 (Jord, Afdampning, Gas and Grundvand) and its applicability to predict concentrations of the chlorinated solvent trichloroethylene (TCE) in indoor air of buildings located on contaminated sites. The questions that are to be answered in this study is whether the modelling tool can be used to predict concentration of TCE in indoor air and what parameters that affect the calculated value the most? The work with risk assessment could be facilitated by validating this modelling tool. The modelling tool was tested on three different contaminated sites in Sweden. When testing the modelling tool, relevant data was used to calculate the concentration of TCE in indoor air and thereafter the results were analyzed. This study showed that the modelling tool underestimated the concentrations of TCE for three out of four tested rooms in the buildings on the contaminated areas for all the tested parameters taken into account. The one room where JAGG 2.1 predicted correct TCE concentrations, compared to the measured result, is considered to have all the right parameters. The parameters are ceiling height, ventilation, the slab-on-grade thickness and the depth where the sample was taken and other geological conditions suitable for a successful calculation. This led to the conclusion that this modelling tool only can be used as an assisting tool and cannot replace environmental engineering studies. The obtained results must also be critically reviewed, before using it for risk assessments. Keywords: JAGG 2.1, modelling tools, vapor intrusion, chlorinated solvents, trichloroethylene.