This investigation was undertaken to provide detailed information on the epidemiology of human parvovirus B19 (B19) infection during pregnancy and childhood in the western part of Germany. Between 1997 and 2004, 40,517 sera from pregnant women aged 17-45 years and 6060 sera from children and young adults were tested for B19 IgG and IgM in our laboratory. In pregnant women, both the history of a 'specific' (OR 7.7, 95% CI 5.2-11.4) and a 'non-specific' rash (OR 3.3, 95% CI 1.5-7.1) was predictive for B19 IgM positivity. The B19 IgG prevalence was 69.2% (4097/5924) in a subgroup of asymptomatic pregnant women screened for B19 antibodies. In children, the age-specific IgG-positivity rate increased from 12.2% (66/541) at 2 years of age to 71.9% (396/551) in those older than 10 years. In conclusion, the prevalence of B19 IgG in pregnant women from the western part of Germany is higher then previously reported. Contact with children aged 3-10 years is a major risk factor for exposure to B19. Pregnant women with the history of a 'non-specific' rash should also be evaluated for acute B19 infection.