The authors hypothesized that parvovirus B19 with its hematotropic effects has the potential to precipitate varying forms of cytopenia in patients prior to or at the diagnosis of acute lymphoblastic leukemia (ALL). Consequently, and in view of the increasing number of cases reported, this retrospective study evaluated, for the first time, the possible role of parvovirus B19 infection in pediatric patients suffering from ALL, by investigating the frequency and clinical relevance of this infection at the time of the malignant diagnosis or, when applicable, during a phase of pre-ALL. Furthermore, a review of reported parvovirus B19 infections in pediatric ALL patients is presented. The serum of 65 consecutive pediatric patients with a diagnosis of ALL was examined for possible parvovirus B19 infection employing the polymerase chain reaction and ELISA techniques. Specific IgG was demonstrated in 30% of the patients. One patient diagnosed with pre-ALL had evidence of parvovirus B19 DNA in the serum during pancytopenia 5 months prior to the onset of ALL. The results suggest that there is an insignificant chance of finding a parvovirus B19 infection in pediatric patients with ALL at the time of diagnosis. However, parvovirus B19 infection may infrequently serve as a prodrome to ALL.