Symmetrical polyneuropathy developed in 2 patients after they had been in contact with acrylamide and methyl n-butyl ketone, respectively. In sural nerve biopsy material from both patients, EM showed frequent focal axonal swellings containing masses of neurofilaments. Some axons undergoing axonal degeneration also were seen. These morphologic features are identical to those produced in experimental animals after exposure to these chemicals and are similar to those found in n-hexane neuropathy and in the 3 reported cases of giant axonal neuropathy. Sural nerve biopsy is an important diagnostic test in identifying cases of peripheral neuropathy caused by these chemicals.