Abstract: AIM　To study the phase I metabolites of phenoprolamine hydrochloride (DDPH) in rat bile. METHODS　DDPH was administered ip to bile duct-cannulated rats. Bile samples were collected before administration and up to 12 h after administration. After being treated with β-glucuronidase, the bile samples were purified and enriched with C-18 SPE columns, and then were analyzed by LC/DAD/MSD. The samples containing synthesized reference standards of DDPH metabolite 1-(2,6-dimethylphenoxy)-2-(3-methoxy-4-hydroxyphenylethylamino)-propane (M₁), 1-(2,6-dimethyl-3-hydroxyphenoxy)-2-(3,4-methoxy-phenylethylamino)-propane (M₂), 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3,4-methoxyphenylethylamino)-propane (M₃), 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3-hydroxy-4-methoxyphenylethylamino)-propane (M₄), 1-(2,6-dimethyl-3-hydroxyphenoxy)-2-(3-hydroxy-4-methoxyphenylethylamino)-propane (M₅) and 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3-methoxy-4-hydroxyphenylethylamino)-propane (M₆) were analyzed by LC/DAD/MSD under identical conditions. RESULTS　The retention times, UV spectra, molecular weights and production spectra (obtained by collision-induced dissociation)of the apparent ions of peak A, B, C, D, E and F in the total ion chromatogram of DDPH treated rat bile sample were consistent with those of M₁, M₂, M₃, M₅, M₄ and M₆, respectively. CONCLUSION　M₁, M₂, M₃, M₄, M₅ and M₆ were identified as the phase I metabolites of DDPH in the rat.