The incidence of contamination of catheters and syringes used during epidural analgesia for parturients and the effectiveness of bacterial filters were investigated. The effect of bupivacaine on bacterial viability and growth was also studied. Syringes in 5/101 cases were contaminated, while catheter tips located in the epidural space were sterile. Organisms isolated were skin commensals and probably originated on the hands of anesthetic personnel. Bupivacaine (0.25%) was bacteriocidal to S epidermidis and Corynebacterium spp at 37C but not at room temperature. These findings illustrate the efficacy of using bacterial filters during continuous epidural analgesia. New syringes should be used for each epidural injection as insurance against seeding of bacteria in the presence of a defective filter.