Florida beefwas sampled during May, 1966, and the first halfof 1967 and analyzed for 137Cs to help define the unusual radioecological situation first suggested by radionuclide levels observed in Florida milk. Cesium-I37 levels in grain-fed beef showed a geographic trend with the highest levels, 110-540 pCi/kg, occurring in the southern and south-central parts of the State and the lowest levels, 55-175 pCi/kg, occurring in the northwestern part. Levels in beef showed the same general geographic pattern shown by levels in milk.These findings and the results reported for Florida milk and dairy feeds indicate that this nuclide is concentrated to higher levels in biological materials in much of Florida than would be predicted from the distribution and levels of fallout deposition and from the average concentration by these media in other parts of the country.