F-19 Magnetic Resonance Spectroscopy (MRS) has been used to quantitate the biodistribution of perfluorocarbon (PFC) blood substitutes in porcine tissues following intraperitoneal administration of a 20% w/v perfluorotributylamine (FC-43) based emulsion. PFC tissue concentrations were determined for spleen, liver and lung tissues from juvenile pigs ranging in weight from 12 to 15 kg. Typical average values (mmoles FC-43/gram tissue) ranged from 0.23-0.39 for spleen; 0.09-0.13 for liver; and 0.09-0.12 for lung. A description of this spectroscopy based quantitation technique will be presented. F-19 MRS is a specific, rapid, and accurate method for measurement of PFC tissue concentrations.