A mixture of perfluoromethyldecahydroisoquinoline (FMIQ) emulsion coupled with anti-CEA (carcinoembryonic antigen) antibody and perfluorotripropylamine (FTPA) was injected into a nude mouse inoculated with human colon carcinoma LS174T. Three days after the injection, in vivo fluorine-19 chemical shift images of the spectral signals of the two perfluorocarbons (PFCs) were obtained simultaneously. The signal intensities and distributions of FMIQ and FTPA were similar in the liver and spleen but different in the tumor. FMIQ was detected in almost the entire tumor, with scattered areas of high uptake. FTPA, however, was detected only in the center of the tumor. The results suggest that F-19 chemical shift imaging of two PFCs, one coupled to antibody and the other not, has potential application in tumor diagnosis.