The effect of baicalein on mucosal ion transport in the rat distal colon was investigated in Ussing chambers. Mucosal addition of baicalein (1-100 µM) elicited a concentration-dependent short-circuit current (I_sc) response. The increase in I_sc was mainly due to Cl secretion. The presence of mucosal indomethacin (10 µM) significantly reduced both the basal and subsequent baicalein-evoked I_sc responses. The baicalein-induced I_sc were inhibited by mucosal application of diphenylamine-2-carboxylic acid (100 µM) and glibenclamide (500 µM) and basolateral application of chromanol 293B (30 µM), a blocker of K_vLQT1 channels and Ba²⁺ ions (5 mM). Treatment of the colonic mucosa with baicalein elicited a threefold increase in cAMP production. Pretreating the colonic mucosa with carbachol (100 µM, serosal) but not thapsigargin (1 µM, both sides) abolished the baicalein-induced I_sc. Addition of baicalein subsequent to forskolin induced a further increase in I_sc. These results indicate that the baicalein evoked Cl secretion across rat colonic mucosa, possibly via a cAMP-dependent pathway. However, the action of baicalein cannot be solely explained by its cAMP-elevating effect. Baicalein may stimulate Cl secretion via a cAMP-independent pathway or have a direct effect on cystic fibrosis transmembrane conductance regulator.