[en] Radiological contamination of the environment is caused by nuclear activities on the globe: nuclear weapon tests and the Chernobyl accident. The transfer of radionuclides to the organism via ingestion is one of the sources of doses obtained by people. To assess the doses received by humans the intake of isotopes with daily diet was defined. The concentration of radionuclides in foodstuffs was determined. The network of Service for Measurement of Radioactive Contamination systematically controls all kinds of important agricultural products such as milk, meat, vegetables, fruit, cereals and forest products: mushrooms, blueberries etc. Measurement stations involved in food monitoring act within Sanitary-Epidemiological Stations, Veterinary Hygiene Units and Chemical-Agricultural Stations. All activities are co-ordinated by the Central Laboratory for Radiological Protection. The level of activity of caesium isotopes has regularly been monitored in collected samples originating from different administrative districts of Poland. Since 1994 the ¹³⁴Cs concentration has been below the detection limit. The activity of ¹³⁷Cs has been measured to determine long-term effect of the accident on the contamination of milk, meat and other foodstuffs. (orig.)