The use of prompt gamma activation analysis (PGAA) as a method for detection of the intestinal rare earth marker, samarium, has been evaluated by comparison with thermal neutron activation analysis (NAA). PGAA detection has significant advantages with respect to its higher reaction cross section and possible rapid experimental turnaround time. Serious disadvantages are lower neutron fluxes available to the target and nonavailability of numerous PGAA facilities. Results of the technique comparisons are generally very good. Pony fecal concentrations of samarium in samples obtained at various times after administration of a marked meal were measured by both techniques. In only one sample did results of the methods differ by more than the experimental errors involved.