Secretory diarrhea remains a major health challenge worldwide. Excessive fluid secretion in the intestine caused by enterotoxins results in activation of luminal Cl- channels on enterocytes. The cystic fibrosis transmembrane conductance regulator (CFTR) protein is the major cyclic adenosine monophosphate (cAMP)-regulated Cl- channel activated in cholera as well as in diarrheas caused by other bacterial enterotoxins. Small-molecule screens have yielded CFTR inhibitors with half-maximal inhibitory concentration (IC50) values as low as 4 nmol/l. The data from proof-of-concept studies in animal models support the development of CFTR inhibitors for antidiarrheal therapy.