We have isolated a novel human cDNA clone that encodes a protein with 80% identity in amino acid sequence to DROER, the enhancer of the rudimentary gene in Drosophila melanogaster. The rudimentary gene product is thought to have significant enzymatic functions in the pyrimidine metabolic pathway, as well as a critical role in development of the wings. The human cDNA, termed ERH, consists of 797 nucleotides, which include an open reading frame of 312 nucleotides encoding 104 amino acids. The ERH gene was expressed in all normal human tissues examined. We assigned the ERH gene locus to chromosomal band 7q34 by fluorescence in situ hybridization.