Abstract: Fluorescent probe compounds comprising fluorescent cholic acid derivative are used for visualizing the influence of a candidate compound on biliary excretion in in vitro or in vivo biological models, including certain probes developed report on the activity of the bile salt export pump (BSEP). Visualization is done on hepatocyte cultures with formed bile canaliculi or on liver systems that are exposed to the fluorescent probes and the candidate compound. Visualization is done by fluorescence microscopy. The probes are particularly suitable for early screening of multiple candidate compounds.