Parvovirus B19 (B19) can cause transient aplastic crisis and lead to acute severe anemia. This study investigated the relationship between B19 and anemia among children <5 years old in the city of Mwanza, Tanzania. An enzyme immunoassay was used to detect B19 IgM- and IgG-specific antibodies among children with various categories of anemia according to the World Health Organization (WHO) guidelines. A total of 265 children with median age of 28.5 months (interquartile range 18-39.5) were investigated. Eighty-six children (32.5%) had severe anemia. B19-specific IgM and IgG antibodies were detected in 24 (9%) and 46 (17.4%) children, respectively. Low hemoglobin (Hb) level (p = 0.031), Plasmodium falciparum infection (p = 0.001) and residing in rural areas (p = 0.025) independently predicted B19 IgM seropositivity. Acute B19 infection decreased Hb level by 1.1 g/dl (p = 0.003). In malaria endemic areas, acute B19 infections should be considered among children with severe anemia from rural areas.