The structural organization of the human gene encoding soluble epoxide hydrolase (EPHX2) was determined. Cosmid clones containing the EPHX2 gene were identified by hybridization of a human genomic library with PCR amplified cDNA to the mouse or human soluble epoxide hydrolase as probes. The gene consists of 19 exons and is approximately 45 kb of which more than 15 kb were sequenced. The coding sequence corresponds to 555 amino acid residues, i.e., one additional residue to those in the reported cDNA sequence. The sized of the introns were defined by sequencing or PCR analysis and they contained various repetitive structure elements as expected.