Inhalation of pollen belonging to the species of Ambrosia may cause hypersensitivity reactions. Feed for wild birds is one of the factors that contribute to the spread of these plants. For this reason an amendment to the Directive on undesirable substances in animal feed (2002/32/EC) was added, in 2010 stating that animal feed made of unground cereals can contain up to 50 mg of Ambrosia spp. seeds per kilogram (UL L 290/54). Due to the lack of data, 40 samples of feed for wild birds were examined with a microscopic method. Ambrosia spp. seeds were found in 20 samples (50%). The number of seeds was from 2 to 146 (10 mg to 774 mg). In accordance with the legislation, results were expressed relative to a feed with the moisture content of 12%. Five samples (12.5%) exceeded the permitted value.