Frequencies for the electrophoretically detectable alleles of galactose-1-phosphate uridyl transferase were determined from 406 neonates in Adelaide. GALT*D and GALT*LA frequencies were 0.054 and 0.027, respectively. The expected proportion of heterozygotes was 15.3%, with a GALT N-D component of 10%. The distinction between GALT*D and GALT*LA is essential for estimation of the expected frequency of GALT DG genotypes, an unknown proportion of which are detected as 'deficient' from neonates on galactosaemia screen.