Zeranol is a xenobiotic anabolic agent with estrogenic growth promoting activities, which is legally used in several countries. However, in the EC the anabolics have been banned since 1986. Because of close structural resemblance the antibody cross-reacts with both zeranol and its main metabolites and with the mycotoxin zearalenone and its main metabolites. The Zeranol-EIA is recommended for the screening of urine samples on the presence of zeranol (100%), taleranol (133%), zearalanone (100%), a

-zearalenol (90%), zearalenone (75%) and ß

-zearalenol (70%). The stilbenes (diethylstilbestrol, hexestrol and dienestrol), 17ß-oestradiol, progesterone and testosterone show a cross-reactivity of less than 0.01%. With this Zeranol-EIA a detection limit of 0.1 ng/ml urine can be obtained.