Hepatitis B virus (HBV) infection is one of the most prevalent public health problems worldwide, and causes 1 million deaths annually. In Bangladesh, information about prevalence of HBV infection is scarce, and there is no available data on HDV infection. We determined rates of HBsAg and anti-HBc seropositivity in asymptomatic, healthy children (n = 181) and adults (n = 354) presenting to referral facilities in Dhaka, Bangladesh, and tested a separate group of HBsAg-positive patients (n = 180) for prevalence of HDV. Testing of serum was also performed for signs of liver disease. Overall, seropositivity of HBsAg and anti-HBc in studied subjects was 3 per cent (16/534) and 21.1 per cent (113/534), respectively. Prevalence of HBsAg was highest in the 5- to 9-year-old (8.5 per cent, 7/82) and 10- to 14-year-old (5.9 per cent, 2/34) age groups. Unlike HBsAg, prevalence of anti-HBc was lower in children (14.9 per cent in those below the age of 15) than adults (24.4 per cent in those aged 20-34 years) (p < 0.05). Most HBsAg-positive individuals were symptomatic (n = 125, 69.4 per cent). A high rate (24.4 per cent, 44/180) of simultaneous infection with HDV was observed among HBsAg-positive subjects, with higher rates in older individuals. Anti-HDV seropositivity rate was similar among asymptomatic (21.8 per cent, 12/55) and symptomatic (25.6 per cent, 32/125) HBsAg carriers. Our data suggest that Bangladesh is of moderate endemicity for HBV infection, and has relatively high rates of co-infection with HDV. Control HBV and HDV infection in Bangladesh may be best achieved by targeting preschool children, which could fit readily within the existing EPI schedule.