Likelihood analysis using the mixed model of quantitative plasma Lp(a) measurements on members of a large pedigree provided evidence that high levels of Lp(a) are inherited as a dominant major gene with polygenic background. The dominant allele frequency was estimated as 0.10. The major gene and polygenic components together accounted for 95% of the variation seen in the measurements. The major gene index and OBP plots, methods that do not allow for the presence of both components, favored the polygenic model over the major gene model as the mode of inheritance. No association was found with any of the lipids, lipoproteins or apolipoproteins considered.