Genomic blot analysis revealed that the nucleophosmin/B23 gene belongs to a multigene family that has about 10 copies per haploid human genome. In searching for human nucleophosmin/B23 functional genes, seven processed pseudogenes (NG1-1.6, NG2-6, NG3-3, NG4-5, NG5-4, NG6-4, and NG7-6) were isolated and characterized. Four of them, NG2-6, NG3-3, NG4-5, and NG7-6, contain the sequences corresponding to the full-length cDNA. NG1-1.6 is 5'-truncated, whereas NG5-4 and NG6-5 are 3'-truncated pseudogenes. Of the seven pseudogenes, NG3-3 clone has the longest 5' untranslated sequence, which contains 104 nucleotides upstream of the translation initiation codon (AUG). Two processed pseudogenes (NG2-6 and NG3-3) have different polyadenylation sites from the mRNA, indicating the usage of alternative polyadenylation signals at the 3' sequence.