The radioactive nucleides detectable in tobacco are derived from natural and anthropogenic sources. Naturally derived radioisotopes relevant for tobacco are 40K, 210Pb and 210Po. Anthropogenic sources include atmospheric nuclear weapon tests and nuclear energy plants and may give rise to increased levels of radioactive 131I, 137Cs, 90Sr and different plutonium isotopes in the environment. Uptake by the tobacco plant and transfer to smoke of the radionuclides are reported. The smoking related radiation dose is compared to the dose an average individual is usually exposed to. The data available indicate that smoking does not substantially contribute to the commonly occurring exposure to radioactive material.