Mutagenicity of two common solvents, 2-methoxyethanol (109864) (MOE) and bis(2-methoxyethyl)ether (111966) (MOE-ether), was studied in various systems. Salmonella-typhimurium was examined for mutations after exposure to up to 33 milligrams (mg) MOE or 94mg MOE-ether per plate. Human embryonic intestinal fibroblasts were observed for unscheduled DNA synthesis after 3 hours exposure to up to 10mg per milliliter (ml) MOE or 19mg/ml MOE-ether. Male Oregon-K-Drosophila- melanogaster were exposed to 25 parts per million (ppm) MOE for 1 hour, 500ppm MOE for 15 minutes, or 250ppm MOE-ether for 2.75 hours. Three generations of offspring were examined for fertility effects and sex linked recessive lethal mutations. CD-rats were exposed to 25ppm MOE or 250ppm MOE-ether for 7 hours for 1 or 5 days. Bone marrow cells were examined for chromosomal damage 6 to 48 hours later. Treated and control males were mated to untreated females at ten weekly intervals. Females were sacrificed 17 days after mating, and dominant lethal effects were assessed by pregnancy examination. Male B6C3F1-mice were exposed to 25 to 500ppm MOE or 250 to 1000ppm MOE-ether, 7 hours daily for 4 to 5 days, then examined after 35 days for sperm abnormalities. No mutagenic effects were observed in S-typhimurium cultures, human fibroblasts, or rat bone marrow cells. The Drosophila sex linked recessive lethal test produced ambiguous results. In rats, high dose groups showed pregnancy frequencies of less than 50 percent for mating weeks 4 to 8, implantation frequencies of 0 to 60 percent of control for weeks 5 to 7, and early death frequencies 1.5 to 2 times control for weeks 5 to 8. Amorphous head sperm abnormalities were increased 2.5 and 10 times in high dose MOE and MOE-ether mice, respectively. The authors conclude that MOE and MOE-ether are only weakly mutagenic, but have considerable effects on male fertility and embryonic development.