The present study examined the effect of Bak Foong Pills (BFP), an over-the-counter traditional Chinese medicine (China registration no. Z980035), on anion secretion and the underlying signaling pathways in normal and cystic fibrosis pancreatic duct cell lines, CAPAN-1 and CFPAC-1, respectively, using the short-circuit current technique. Apical addition of BFP ethanol extract (600μg/ml) induced a fast transient ISC peak that was followed by a slower but more sustained increase in ISC in CAPAN-1 cells. However, the response to BFP in CFPAC-1 was predominantly the first transient peak. Apical addition of DIDS (200μM) inhibited the first peak by more than 60% in both cell lines without significantly affecting the second ISC rise. More than 85% of the BFP-induced first transient in both cell lines was inhibited when extra and intracellular Ca2+ was chelated or emptied by pre-treatment with BAPTA (100μM) and thapsigargin (10μM), respectively. Acute addition of PMA (1μM), a PKC activator, blocked more than 95% of the BFP-induced first peak in both cell lines, consistent with previously reported PKC modulation of Ca2+-dependent pancreatic anion secretion. The BFP-induced second ISC rise in CAPAN-1 could be inhibited by 73.6% and 71.13% by pretreatment of the cells with MDL-12330A (20μM), an adenylate cyclase inhibitor and Rp-cAMP (200μM), a cyclic AMP antagonist, respectively. However, less than 25% of the ISC was inhibited by combined treatment with BAPTA and thapsigargin. The second rise was also completely blocked by DPC (2mM) or Glibenclamide (1mM). The results indicate that BFP ethanol extract stimulates pancreatic duct anion secretion in normal and CF cells via different signaling pathways involving both Ca2+ and cAMP.