Intravenous diffusion hepatography with99mTc-pertechnetate was used to evaluate the diffusion patterns of solitary hepatic masses which had little or no perfusion demonstrable by the113mIn perfusion study. The scintiphotos of 21 proven cases were analyzed. The results indicate that the diffusion study may help to differentiate hepatic abscesses, especially amebic abscesses, from congenital solitary cysts. This simple and innocuous approach would be another step toward increasing the specificity and accuracy of the nuclear diagnosis of hepatic mass lesions.