Three previously undescribed mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene have been documented in patients with hereditary non-spherocytic hemolytic anemia (HNSHA). In none of the cases have we been able to obtain a sufficient volume of blood to characterize the residual enzyme biochemically. "G6PD Calvo Mackenna" was due to an A-->G transition in cDNA nucleotide 1138 creating an Aat II site and resulting in a substitution of valine for isoleucine at amino acid 380. "G6PD Riley" was due to a T-->C transition at cDNA nucleotide 1139 also changing the 380 isoleucine, in this case to a threonine. "G6PD Wisconsin" was due to an C-->G transversion in cDNA nucleotide 1177, destroying a Aci I site and resulting in a substitution of glycine for arginine at amino acid 393. All of these mutations were in exon 10, where mutations that cause HNSHA appear to be clustered. We present a list of the 83 mutations of G6PD that have been documented to the end of April, 1995.