To select compounds for carcinogenesis study, a class of 323 ether compounds deemed to be commercially significant was investigated. Review articles, compendia, and other reports of experimental data were used to gather evidence of potential carcinogenicity of the compounds. This original list was reduced to 176 compounds after consulting previous or currently underway carcinogenicity test results, or by determining that the compounds were not produced in the United States in commercial quantities. These 176 compounds were divided into three categories (high, moderate, or low) of potential human exposure. The 176 compounds were further subdivided into 11 chemical structure subclasses covering the range of structural configurations in these ethers. These classes were: alkoxyphenyl ethers, extended phenyl ethers, fused aryl ring system ethers, tetrahydrofurans, simple aliphatic ethers, ring containing aliphatic ethers, halophenoxyalkyl ethers, pyrans and benzopyrans, diaryl ethers, N-heterocyclic ring systems, and ethers of uncharacterized structure. Based on the suspicion of possible carcinogenic activity and evidence indicating potential exposure, the following eight chemicals were nominated for further investigation: methyleugenol (93152), isoeugenol (97541), 2- isopropoxyphenyl-N-methylcarbamate (114261), estragole (140670), 2- hydroxy-4-methoxybenzophenone (131577), tetrahydrofuran (109999), methyl-vinyl-ether (107255), and diphenyl-ether (101848).