The total length of railway line in Croatia is approximately 3.000,000 kilometres.Considering the age of the railway lines, there is often a need for reconstruction of part of the railway.The environmental impact assessment of reconstruction of the railway line is a very important part of environmental protection. The primary basis for the assessment is The environmental impact study.The environmental impact study of the reconstruction of railway includes an analysis of the parameters and data on environmental components, detects negative parameters and their impact on the environment, and provides environmental protection measures and environmental monitoring program during designing and reconstruction of the railway, and during the use of the railway line after reconstruction.The aim and purpose of the environmental impact assessment of reconstruction of the railway line, through the proper procedure, is to assess the impact of the railway on the environment and to determine the necessary environmental protection measures, in order to reduce negative impact to a minimum and to achieve the preservation of environmental quality.