Diagnostic biopsies of 1,140 previously untreated patients with Hodgkin's lymphoma from the German Hodgkin Therapy Trial were evaluated by a panel of 4 histopathologists. Each case was classified by consensus of the four according to an extended Rye-System including the diversifying of NS.HD and the unclassifiable cases. The interobserver agreement rate was 92.1% among the panel members regarding the final classification. Primary Hodgkin diagnosis was approved in 91.7% (1045/1140 cases). The distribution of the 1,140 cases within this system was (in %) as follows: 2.7 LP.HD, 57.9 NS.HD, 17.3 MC.HD, 0.7 LD.HD, 13 HD of unclassifiable subtypes, 6.3 of not certain HD, 1.9 Non-Hodgkin Lymphoma, 1 case of non malignancy. Grading of NS.HD into 2 subgroups according to the British classification differed conspicuously by 84.5% versus 15.5% and 71.6% versus 28.4% in British results. This divergency is explained by interobserver disagreement ranking from 43% to 85%.