The accumulation of Tc-technetium-labelled liposomes in abscesses was studied. Abscesses were produced in the thighs of albino rats by intramuscular injection of . After 4 days these abscesses were used to determine the localisation of Tc-technetium-labelled anionic, cationic and neutral liposomes in the abscess area. This was achieved by radionuclide images produced by a gamma camera and an associated data-processing system. There was a pronounced uptake of Tc-technetium-labelled anionic liposomes in the abscess area compared with the corresponding unaffected thigh. Similar uptake was not shown by the Tc-technetium-labelled cationic and neutral liposomes. Abscess uptake of anionic liposomes was maximal at or before 30 min after injection and was not enhanced by prior opsonisation with aggregated rat immunoglobulin.