The International Gamma‐Ray Astrophysics Laboratory (INTERGAL) is a candidate for the next ESA medium‐size scientific mission to be launched in 2000. INTEGRAL addresses the fine spectroscopy and accurate positioning of celestial, gamma‐ray sources in the energy range 15 keV to MeV. A joint ESA‐NASA assessment study has been completed recently. The slope of this study covered the mission’s scientific prospects; the overall payload concept; payload accommodation and system analysis and an investigation of possible mission scenarios within the framework of an international collaboration.