The addition of epinephrine to solutions containing fentanyl and bupivacaine for epidural infusion has been shown to improve the quality of analgesia. However, this admixture is not available commercially in the United Kingdom. Moreover, stability data applicable to UK practice for this admixture are limited. This study investigated the stability of fentanyl 2 microg.ml(-1) plus bupivacaine 1 mg.ml(-1) in PVC bags with and without epinephrine 2 microg.ml(-1) over a period of 184 days both at room temperature and at 4 degrees C. All infusions were found to be stable over the study period (> 90% remaining) using stability-indicating High Performance Liquid Chromatography (HPLC) methods, with no changes in physical appearance or pH (range 4.5-4.2). The infusions were prepared using standard pharmaceutical products, so facilitating the batch preparation of epinephrine, fentanyl and bupivacaine epidural solutions by hospital pharmacy departments.