The von Willebrand factor pseudogene, previously mapped to chromosome 22, was sublocalized by in situ hybridization using as probe a von Willebrand factor cDNA fragment completely contained in the pseudogenic region. Chromosome spreads were from a patient carrying a unique balanced de novo translocation 46,X,t(X;22)(pter;q11.21). Silver grain analysis indicated that the human von Willebrand factor pseudogene is located on 22q,11,22-q11,23, a region relevant for several somatic and constitutional chromosomal alterations.