The absolute fission yields of 22 nuclides for~lled in the thermal neutron fission of U233 have been ~neasured radiochernically. Disintegration rates were measured by 4~ @-proportional counting techniques. The identity of each nuclide was established by che~llical separations and decay characteristics as determined by 4~ p-counting and -,-ray scintillation spectrometry. The reaction Co6"n,-,)Co" ovas used as a neutron flux monitor. Yields were calculated on the basis of u~U'33/ucC05q = 524/36.3.