The genomic organization of the human 51-kDa subunit gene (NDUFV1) on human Chromosome (Chr) 11q13 was determined. The NDUFV1 gene consists of 10 exons. Exon 1 encodes for the 20-amino-acids-long import sequence, and exon 1 through 10 codes for the 444-amino-acids-long mature protein. The protein sequence is highly conserved between human and bovine. Northern blotting analysis showed that the NDUFV1 gene expression varies widely among tissues and that in testis a unique mRNA species is present. In comparison with the other complex I flavoproteins, the expression of the 51-kDa gene in pancreatic tissue is high.