Abstract: Objective: To study the feasibility of using ¹⁹F nuclear magnetic resonance （NMR） spectroscopy to monitor CD transgene expression in human colon cancer cell line. Methods: The cell line SW1116 was transfected with a gene coding for cytosine deaminase （CD from E.coli） by retroviral mediated method. The assessment of expression of CD gene in colon cancer cell line was carried out by ¹⁹F-NMR spectroscopy drug sensitivity to 5-FC in vitro and in vivo. Results: ¹⁹F-NMR spectroscopy showed that incubation of cultured CD+cells with 774 μmol/L 5FC for 24 h, the spectrum of intact cells shows two broad resonances corresponding to 5-FC （chemical shift relative to trifluoroacetate δ-91.7） taken up into cell, 5-FU（δ-93.3） produced by the action of cytosine deaminase. The resulting SWCD₂ cell line was more sensitive to the prodrug 5-fluorocytosine （5-FC）; IC₅₀=66 μmol/L, compared to parent cancer cells SW1116;IC₅₀ =16 000 μmol/L. Conclusion: The feasibility of using 19NMR spectroscopy to noninvasively monitor CD gene expression in human colon cancer was demonstrated. This capability provides an new approach for measuring gene expression that will be useful in clinical gene therapy trials.