Cyclopiazonic acid (CPA) is a toxic indole tetramic acid that has been isolated from numerous species of Aspergillus and Penicillium. It has been found as a natural contaminant of cheese, corn, peanuts and various feedstuffs. Historically, thin-layer chromatography has been the most widely used method for quantitative determination of CPA in fungal cultures and agricultural commodities. Several liquid chromatographic (LC) and spectrophotometric methods have also been used, but these require extensive, time-consuming cleanup procedures to achieve accurate quantitation. More recently, enzyme-linked immunosorbent assays (ELISA) have been developed for quantification of CPA, and an immunoaffinity column (IAC) has been developed for cleanup of sample extracts prior to quantification by ELISA or LC. In applying the IAC to the cleanup of peanut extracts, recovery of CPA from spiked samples ranged from 83.7% to 90.8%, and the method was successfully applied to the analysis of peanuts that were naturally contaminated with CPA.