A population sample of 5,202 persons comprising normal, healthy individuals from three laboratories in Copenhagen was used for estimating HLA-A, -B antigen, gene, and haplotype frequencies, besides delta-values and their standard errors. The serum panels used allowed the determination of a total of 273 HLA-A, -B haplotypes, and the most significant delta-values were in agreement with those found in other Caucasian populations. The methods used for the calculations of frequencies, delta-values, and standard errors are described.