Examination of 330 samples of animal feed ingredients for the presence of a number of mycotoxins has been carried out. These samples were drawn from 186 animal feed mills in the United Kingdom. Aflatoxin B1 was the mycotoxin found most frequently, occurring in most samples of rice bran, maize products, palm kernels and cottonseed, but not in only 3 out of 20 samples of sunflower, in 1 out of 20 samples of soya and in no samples of peas, beans or manioc. Analytical difficulties were met with some combinations of commodity and mycotoxin and all results are uncorrected for recovery. The highest level was detected in a sample of maize gluten: 41 micrograms/kg of aflatoxin B1 (47 micrograms/kg total aflatoxins). Maize products also frequently contained fumonisins B1 and B2 at levels up to nearly 5,000 micrograms/kg in total and zearalenone up to a maximum level of 500 micrograms/kg. Ochratoxin A and citrinin were found in approximately 20% of wheat and barley samples. One sample of barley contained ochratoxin A at a level of 102 micrograms/kg and citrinin at a level of 8 micrograms/kg. Low levels of ochratoxin A also occurred in a few samples of other ingredients: rice bran, palm kernel and beans. Sterigmatocystin at 18 micrograms/kg was found in one sample of organically grown wheat and a trace amount of zearalenone in one sample of manioc. Multi-mycotoxin contamination also occurred, particularly in some samples of maize for which 19 out of 50 samples contained both aflatoxins and fumonisins.