Between January 1, 1991, and December 31, 1993, bovine urine was collected for analysis of beta 2-adrenergic agonist residues. A multiresidue method was developed that was capable of detecting clenbuterol, clenpenterol, clenproperol, mabuterol, mapenterol, bromobuterol, tulobuterol, and salbutamol through enzyme-linked immunosorbent assay, liquid chromatography (LC) with photodiode array detection, and gas chromatography with mass detection in electron impact mode with selective-ion monitoring. Among 1031 samples, 24 contained clenbuterol and 1 contained salbutamol. The results confirm that clenbuterol is the beta 2-adrenergic agonist most used as bovine growth promoter in Portugal.