We present a consanguinous couple whose three of four children are homozygous for a rare slow alpha 1 antitrypsin allele PI*W. All three children had abnormal liver function in infancy and two died in infancy of liver disease. The eldest child and both parents were heterozygous for the PI*W allele and were unaffected. Therefore, although serum levels are not markedly reduced, homozygotes appear to be at increased risk of developing liver disease.