The time course of production, specificity, and analytical potential of anti-zearalenone polyclonal rabbit antibody synthesized by formaldehyde condensation and conjugated to bovine serum albumin were investigated. The relative cross-reactivities with natural analogues were: zearalenone, 100%; alpha-zearalenol, 0.15%; and beta-zearalenol, < 0.02%. With synthetic analogues: zearalanone, 31.7% and alpha-zearalanol, 0.12%. An enzyme immunoassay for zearalenone with a sensitivity of 0.1 ng/ml was developed on the basis of these antibodies and solid-phase conjugates homologous to the immunogen in the method of synthesis.