The frequency of chromosome aberrations was determined in the bone marrow cells of Sprague-Dawley rats exposed by oral gavage to a single dose of 2-ethylhexyl diphenyl phosphate. Forty eight animals per group (24 male and 24 female) received dosages of 0, 1500, 5000 and 15000 mg/kg test article in corn oil. Statistically significant (KW-ANOVA, p < 0.05) differences in the percent aberrant cells, mean number of aberrations per cell, mean mitotic index, or mean modal number were not observed at any dose level. The dose levels were chosen based on the results of a preliminary range finding study and the previously determined LD50. Clinical observations of dose related toxicity during the test included soft feces, urine stains, depression, rough coat, red stains on nose and eyes, hunching and decreased body weights. Additionally, mortality was observed in five animals in the mid dose group.