Amniocentesis was performed in two women heterozygous for adrenoleukodystrophy (ALD). One fetus was male, and the hexacosanoic acid (C26) level in the cultured amniotic cells was 0.808 microgram per mg of protein, compared to 0.104 +/- 0.069 (S.D.) in controls. Pregnancy was interrupted at 22 wk gestation. The fetal adrenal cortex showed the ultrastructural inclusions characteristic of ALD and C26 accounted for 35% of the fatty acids in the cholesterol esters extracted from this tissue, more than one thousand times control. The second amniocentesis was performed in a woman who was also heterozygous for an electrophoretic variant of glucose 6- phosphate dehydrogenase (G6PD), and a member of a kindred showing genetic linkage of loci for ALD and G6PD. The fetus was female and the C26 level in cultured amniotic cells was 0.577. Pregnancy was interrupted at 11 wk for reasons unrelated to ALD. Study of C26 level and G6PD type in cultured fetal tissues confirmed heterozygosity for ALD.