An animal model to study subphrenic fluid collections is presented. Performance of single photon emission computed tomography (SPECT) for detection of subphrenic fluid collections was compared to that of liver-lung scintigraphy and transmission computed tomography (TCT). TCT detected a water volume of 25 ml in the right subphrenic space. This volume was barely seen using SPECT and not detectable on scintigraphy. Differences in performance of the three imaging modalities are discussed.