Sequence differences within the pig apoB gene can be used to identify rapidly four of eight known pig apoB alleles, designated LPB1-LBP8. We describe the use of gene amplification, followed by endonuclease digestion and agarose gel electrophoresis, to discern size and restriction site differences. LPB5, a common allele associated with reduced low density lipoprotein clearance and hypercholesterolaemia in pigs, is identified by a 283-bp insertion in intron 28. LPB3 and LPB7 are distinguished by a unique HindIII site; LPB8 shares a unique HincII site with LPB5. This method facilitates identification of the apoB genotype of pigs used in lipoprotein research and allows for further investigation into the association of particular apoB alleles with lipoprotein metabolism abnormalities.