Fumonisins, a group of mycotoxins produced by the ubiquitous fungi Fusarium moniliforme and F. proliferatum, were first identified about eight years ago. They have been shown to cause a variety of health effects in animals, including epidemiological evidence of esophageal cancer in humans. Cattle are less sensitive to ill effects than horses and swine. Fumonisins are common contaminants of low quality grain fed to cattle. Culture material containing fumonisins (FB1, FB2, and FB3) was mixed into the total diet and fed for 14 days to two midlactation Jersey cows to determine if fumonisins are excreted in milk. The dietary equivalent of fumonisin was approximately 75 ppm and the two cows consumed an average of 3 mg fumonisin B1/kg body weight (bwt)/day. Fumonisins were not detected in any of the milk samples by two analytical laboratories using methods with a sensitivity of 5 ng/ml. Except for transient diarrhea at the beginning of the contaminant feeding period and an increase in serum cholesterol, clinical and hematologic changes were not observed in the animals. The appearance or carry over of fumonisins from feed to milk in dairy cows does not appear to be significant and likely not a hazard or food safety concern for humans.