Clenbuterol belongs to the group of agonists. In livestock production clenbuterol improves the meat/fat ratio in fattened animals or accelerate the growth. Up to now agonists have not been authorized as adjuvants for fattening. In addition to its lipolytic and anabolic effect, clenbuterol has a relaxing effect on non-striated musculature on which is based its therapeutic use as an antiasthmatic and a tocolytic agent. When employed as a fattening adjuvant, as compared with the therapeutic use, clenbuterol is administered in a 5 to 10 times higher dose. Therefore, it is possible that clenbuterol residues may lead to a risk for consumers after illegal administration.Using the clenbuterol monocalantibody, it is possible to detect clenbuterol and other agonists in urine, muscle and liver both rapidly and with accuracy.