Tissue kallikrein of colon mucosa is synthesized rapidly, and this synthetic process can now be examined in relation to hormonal or dietary manipulations or pathological circumstances that affect intestinal ion transport. Although the identical renal tissue enzyme is known to be enriched in membranes of distal convoluted tubular epithelial cells, the precise localization of the intestinal enzyme is uncertain. An understanding of the intestinal cellular locale of kallikrein will help in defining its local role. That tissue kallikreins can be inhibited by monovalent cations and some drugs (e.g., amiloride) and that kallikrein inhibitors affect cation transport across epithelial surfaces containing such enzymes must be reconciled with the new observations of kinin-induced chloride secretion. Extracellular calcium, eicosanoid synthesis, and cyclic nucleotide production are involved in the secretory response to kinins, although an absolute requirement for intact eicosanoid synthesis may not exist.