1. The major biliary metabolites of flavanones in the rat have been identified by chromatographic and spectral methods. 2. Evidence is presented that flavanones and flavanone glycosides, following oral or parenteral administration, undergo glucuronylation and are selectively excreted via the bile. 3. Flavanone glycosides but not unconjugated aglycones may be excreted to a significant extent in bile. 4. The percentage of parenterally administered flavanones excreted in bile varies inversely with the amount administered.