The German Study Group Gastrointestinal Lymphoma (GSGL) is an association of all major groups that have scientifically been investigating the treatment of primary lymphoma of the stomach and intestine in Germany. First result of this co-operation is the study protocol DSGL 01/2003 "Behandlung primärer Lymphome des Magens - Therapieoptimierung in den Stadien I und II bei indolenten und aggressiven Lymphomen" ("Treatment of primary lymphoma of the stomach - therapy optimising in stages I and II of indolent and aggressive lymphoma")