Epidemiological analyses indicate a decreasing level of hepatitis D (HDV) infections in most developed countries during the last 15 years. Romania, however, is one of the European countries that still has high morbidity from HDV; this study was performed in order to estimate the HDV prevalence in the Bucharest area. Three thousand four hundred sixty-one hepatitis B (HBV) infected patients were invited to participate and 1,094 were recruited. Serum anti-HDV IgG was detected in 223 patients indicating a hepatitis D seroprevalence of 20.4% (95% CI = 18.1–22.9) in patients chronically infected with HBV, less than that seen in previous studies. Seroprevalence was not gender related, but patients over 40 years were more likely to have anti-HDV antibodies, RR = 1.9 (1.2; 3.0). Detectable hepatitis D viraemia was found in 67.7% of the patients who were positive for anti-HDV. The HDV genotype was characterized for 40 isolates; all were very similar and belonged to genotype 1. Serum HBV-DNA was detectable less frequently in patients positive for anti-HDV than in patients infected with HBV alone: 68.5% versus 89.3%, OR 3.9 (1.7; 10.0), but the extent of this HDV replicative dominance varies with the sensitivity of the HBV-DNA detection. 19.3% of the subjects who tested positive for anti-HDV IgG had a HBV-DNA level higher than four logs. This high prevalence prompts the need for better HBV vaccination coverage and measures to prevent super infection with HDV in patients infected with HBV. J. Med. Virol. 85:769–774, 2013. © 2013 Wiley Periodicals, Inc.