The purpose of this study was to evaluate the oral toxicity of 35 cs. polydimethylsiloxane (PDMS) fluid to determine health hazards when used as a fat substitute in certain foods. Three groups of 15 male and 15 female CD-1 mice were administered 0, 5, or 10% 35 cs., PDMS fluid in the diet for 90 days. Body weights were recorded on day zero of the study and body weights and food consumption were recorded weekly throughout the study. All animals were observed daily for signs of toxicity, general appearance, behavior, and mortality. Stools were examined visually for coating and consistency, and the perianal region was examined for evidence of anal leakage of the test material. Gross necropsy and histopathology were performed following sacrifice. Most animals in the 10% dietary group exhibited oily fur, and most anal leakage was seen in females in the 10% dietary group. There were significant increases in food consumption in treated groups compared to controls; with the greatest consumption seen in the 10% dietary group. No noted changes in stool consistency or coating were observed in any treated animals. No deaths or behavioral abnormalities were observed and there were no significant differences in body weights or organ weights. No significant treatment related effects were observed during necropsy or histopathological examination.