Summary: A radiochemical extraction procedure for the separation of tellurium isomers has been used to isolate an activity of 12.45 ± 0.28 minute half-life growing into samples of fission product tellurium. This activity is assigned to the ground state of 133Te as it is shown to arise in the decay of 54-min component present in the fission-product tellurium and to decay to form the 21-h 133I. The gamma-ray spectrum of 133Teg shows prominent photopeaks at 0.307 ± 0.01, 0.406 ± 0.01,1.335 ± 0.01,1.709 ± 0.02, and ≈ 1.85 MeV.