AbstractReversed phase HPLC methodology has been developed for separation of peptide leukotrienes and indomethacin in porcine bile. Reproducible recoveries were obtained using radioactive leukotrienes ([3H]LTC4, 57.1 ± 2.5%; [3H]LTE4, 62.7 ± 1.9%; [3H]LTD4, 54.3 ± 2.7%). Radioimmunoassay of column eluant demonstrated that as little as 300 pg of exogenous leukotrienes could be measured in bile fluids, with similar recoveries. Analysis of bile sampled 60–90 min after initiation of experimental endotoxic shock in indomethacin treated pigs revealed a leukotriene concentration of 5.24 ± 1.16 ng/mL(LTD4). This was significantly greater (p<0.05,n= 3) than that observed in samples collected prior to endotoxin (0.42 ± 0.23 ng/mL), or from untreated animals (0.85 ± 0.51 ng/mL). This method is thus applicable to investigation of the role of 5‐lipoxygenase products in porcine models of human disease, including shock conditions such as endotoxaemia, during cyclooxygenase inhibition by ind