Female beagles dosed once with encapsulated 14C-bunolol (10 mg/kg) excreted 61% of the isotope in urine in 24 hr. The pooled urine contained a minimum of 18 labeled compounds. Two previously unknown metabolites were purified and were identified by UV and mass spectral data; they were hydroxybunolol (10.1% of urinary radioactivity) and hydroxydihydrobunolol (9.8%). The urine also contained bunolol (0.7% of urinary carbon-14), dihydrobunolol (0.5%), conjugated dihydrobunolol (2.8%), beta-(5-oxytetralonyl)lactic acid (16.3%), and (5-oxytetralonyl) acetic acid (7.1%).