A processed pseudogene for hexokinase II (HKII), the first such reported for a member of the hexokinase gene family, was isolated from a human genomic library by using a rat HKII cDNA as a probe. The pseudogene contains a region that is identical to the open reading frame of the human HKII cDNA at 97% of the nucleotide positions, but it contains several frameshift mutations, small deletions and insertions, and several stop codons. The human HKII pseudogene is located on the X chromosome and is integrated into a long interspersed nuclear repetitive DNA element (LINE). We estimate that this integration event occurred approximately 14-16 Myr (million years) ago.