Technical Abstract: The consumption of ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), common juniper (Juniperus communis) and Monterey cypress (Cupressus macrocarpa) causes abortions in pregnant cattle. Recent studies have identified isocupressic acid as the primary abortifacient compound in these plants. In vitro and in vivo studies using rumen and blood have shown isocupressic acid rapidly metabolized to agathic acid dihydroagathic acid and tetrahydroagathic acid. Rapid and sensitive diagnostic techniques are needed to identify poisoned animals, study toxicokinetics, and to elucidate the mechanism of isocupressic acid-induced abortion in cattle. In this study four competitive inhibition enzyme-linked immunosorbent assays for isocupressic acid and its sera metabolites were developed using-polyclonal antibodies. One assay is specific to isocupressic acid while the other three assays show cross reactivity with agathic acid, dihydroagathic acid, tetrahydroagathic acid in addition to isocupressic acid. The assay specific for isocupressic acid had a limit of detection of 44.1 pg. The other assays which demonstrated cross reactivity with the isocupressic acid blood metabolites also had comparably low limits of detection. One assay was used to follow the absorption and elimination profile of isocupressic acid metabolites in both blood and urine after oral dosage of a cow with common juniper. The simple extraction ELISA methods described in this paper demonstrate the potential of using these tools for the rapid screening of biological samples for the presence and levels of isocupressic acid and its blood and urine metabolites and will be beneficial in the diagnosis of animal poisoning and pharmacological studies.