Studies of the metabolism and disposition of fluoropyrimidine drugs using fluorine-19 nuclear magnetic resonance spectroscopy as the analytical technique are reviewed. These studies concern essentially the anti-neoplastic drugs 5-fluorouracil and 5’- and 2’-deoxy-5-fluoroudrine and the antimycotic drug 5-fluorocytosine. We discuss the value and limitations of this technique in the analysis of metabolites in biofluids and excised tissues (in vitro studies), isolated cells and isolated perfused organs (ex vivo studies) as well as in vivo in both animals and man.