A technique referred to as 'linked-column immunoassay clean-up', was developed for the simultaneous determination of aflatoxins and ochratoxin A in a range of dry cereal-based pet foods and wild bird food. In addition a method also based on clean-up using immunoaffinity columns was used for the determination of fumonisin mycotoxins in samples known or suspected to contain maize. One hundred samples of pet foods consisting of 35 samples of domestic bird seeds and 15 samples of wild bird food were examined for aflatoxins B1, B2, G1 and G2 and ochratoxin A. Twenty samples of these samples were also examined for fumonisins B1 and B2. Limits of detection were about 0.5 micrograms/kg for each aflatoxin and ochratoxin A and 3 and 8 micrograms/kg for fumonisins B1 and B2 respectively. Eighty-four percent of the samples contained no measurable concentrations of mycotoxins. A low level of aflatoxin B1 was found in a sample of cat food and a concentration of 370 micrograms/kg aflatoxin B1 in one sample of peanuts marketed for wild birds. Ochratoxin A was detected in 10% of samples but in low concentrations, the highest of 7 micrograms/kg occurring in a sample of bird food. Fumonisins were found in 30% of the 20 samples tested with a maximum of 750 micrograms/kg total fumonisins being found in a sample of cat food. Five samples each of dog and cat foods were examined for mould count and fungal species as received and after storage under controlled simulated damp conditions. Mould counts in all 10 samples examined were very low when received. The samples in which moisture content had been increased contained visible mould after storage. Penicillium, Eurotium and Aspergillus were the predominant species. However, no ochratoxin A or aflatoxins were detected in these spoiled samples.