[en] Lena_Win is a program for dispersion and dose calculations, mainly connected to accidents in nuclear facilities. Besides that, it may, however, also be used for other kinds of releases. It is designed to be used both for training purpose, and in real situations. Great care has therefore been taken to ensure a simple and quick handling of the program, also in difficult situations. The program is a true Windows application, and works with version 3.0 and higher of Microsoft Windows. It was developed at the Swedish Radiation Protection Institute (SSI) during 1991-1992, and is used by the institute in its regular work. Lena_Win is part in a larger system to handle accidental situations. An important part of this system is a database and a database handler to manage all kinds of measured data after a release. Lena_Win has functions to display data taken from this database on maps