Summary. Hepatitis D virus (HDV) or delta hepatitis has mainly been studied in Asian and Mediterranean cohorts, but data on virological and clinical characteristics of HDV-infected Central and Northern European patients are limited. We investigated virological patterns, as well as biochemical and clinical features of liver disease in 258 HDV infected patients recruited over a period of 15 years at Hannover Medical School. Virological parameters were compared to 2083 anti-HDV negative hepatitis B surface antigen (HBsAg) positive individuals. In this cohort, (i) HDV infection was associated with both suppressed hepatitis B virus (HBV) and hepatitis C virus (HCV) replication, (ii) the suppression of HBV-DNA and HCV-RNA was not related to HDV-RNA replication, (iii) mean HBsAg levels did not significantly differ between HBV-monoinfected patients and individuals with delta hepatitis, (iv) HCV coinfection was rather frequent as about one third of our delta hepatitis patients tested anti-HCV positive, however, without being associated with more advanced liver disease, (v) delta hepatitis patients presented in a high frequency with an advanced stage of liver disease, and (vi) the course of delta hepatitis did not differ between Turkish-born, Eastern European (EE)-born and German-born patients. In summary, in this cohort of patients which is the largest so far Central European single centre group of delta hepatitis patients, we confirm the presence of frequently severe disease and describe novel virological profiles which require consideration in the management of this difficult to treat group of patients.