The aim of this study was to demonstrate the accumulation of I-131-labeled ornidazole (I-131-ORN) in experimental abscesses. I-131-ORN was prepared by electrophilic radioiodination of ORN, using radioiodide in the presence of Iodogen(R). An in vivo inflammation model was prepared by intramuscular injection of turpentine into the thigh of rabbits. Four days later I-131-ORN was intravenously administered to rabbits. Serial scintigrams were performed at different periods, using a Sophy DX Gamma Camera. I-131-ORN was visualized at 10 min after injection. I-131-ORN was also administered intraperitoneally to rats with turpentine-induced inflammation, for quantitative biodistribution studies. Counts of selected tissues were taken by a NaI(TI) scintillation detector (gamma counter) after rats were decapitated. The target-to-non-target muscle ratios were 2.5, 2.6, 2.9 and 1.9 at 1, 3, 5 and 24 h, respectively. (C) 2000 Elsevier Science Ltd. All rights reserved.