The neurotoxic effects of some aliphatic carbon compounds were studied. Test chemicals included 2-hepatone (110430), 3,5- heptanedione, 2,5-hexanedione (110134), 2,5-hexanediol (2935446), 2,4-hexadione, 2,3-hexanedione, 1,6-hexanediol (629118), glutaraldehyde (111308), 1,4-butanediol (110634), and acetone (67641). Rats were given the test compounds in drinking water and body weight, clinical condition, and fluid intake were recorded biweekly for 4 to 29 weeks. At the end of treatment, animals were autopsied. Rats treated with 1,4-butanediol initially lost weight, but gained weight normally after 8 weeks of treatment. Treatment with 2,5-hexanedione or 2,5-hexanediol caused decreased weight gain throughout the experiment. None of the other test chemicals affected weight gains. Tissues from rats treated with 2,5- hexanedione and 2,5-hexanediol showed giant axonal swelling in the central and peripheral nervous systems. Secondary demyelination and fiber breakdown were also noted in the peripheral nervous system. Tissues from rats treated with all other chemicals were normal. The authors concluded that 2,5-hexanedione and 2,5-hexanediol produce distal peripheral neuropathy in rats.