Intestinal cells from human colorectal adenocarcinomas have been established in culture as monolayers of homogeneous polarised cells on permeable filters with various degrees of cell differentiation. These cell lines allow to avoid some of the difficulties of studying water and electrolyte transport through whole intestinal tissue or isolated intestinal cells. Cell lines, such as Caco-2, T-84, HT-29, HRT-18 which exhibit electrogenic chloride secretion induced by various hormones, neurotransmitters, enterotoxins, and other chemical compounds, can be used to study basic biochemical mechanism and their interrelation in the process of chloride secretion which is associated with many diarrhoeal diseases. Identification and use of cell lines having absorptive properties will equally contribute to the understanding of absorptive processes, their regulation and biochemical basis. Cell lines in which both secretory and absorptive processes coexist are valuable for understanding the complex interrelation of the two principal processes of transport mechanism including its biochemical and molecular correlates. Intestinal cell lines can also be used for screening efficacies of potential secretagogues and antisecretagogues.