Purpose: Segmental parenchymal excretion delay on Tc- 99m DISIDA scan is caused by intrahepatic bile duct obstruction. However, the diagmostic value for intrahepatic bile duct obstruction is unknown. We conducted this study to assess the positive predictive value of segmental excretiom delay for the diagnosis of intrahepatic bile duct obstruction, and additional benefit over other noninvasive radiologic studies. Materials and Methods: The study population consisted of 43 patients (48 scans) Who showed segmental parenchymal excretion delay on Tc-99m DISIDA scan. The results of abdominal CT or ultrasonography, which was done within 1 month of Tc-99m DISIDA scan, were compared with scintigraphic findings. Results: The etiology of segmental parenchymal excretion delay was determined by ERC or PTC in 31 scans, and follow-up studies in 13 scans. No causes were identified in 4 scans. The positive predictive value of segmental parenchymal excretion delay for intrahepatic bile duct obstruction was 92% (44/48). On the other hand, 13% (5/38) of CT and 28% (5/18) of ultrasonography were normal. In 18% (7/38) of CT and 17% (3/18) of ultrasonography, only intraheipatic bile duct dilatation was noted without any diagnostic findings of intrahepatic bile duct obstruction. Conclusion: Segmental parenchymal excretion delay on Tc-99rn DISIDA scan had a high positive predictive value for the diagnosis of intrahepatic bile duct obstruction. Tc-99m DISIDA scan may be useful for the diagnosis of intrahepatic bile duct obstruction, especially in patients with nondiagnostic CT or ultrasonography. The diagnostic usefulness need to be confirmed by further prospective studies. KW: Tc-99m DISIDA, Segmental parenchymal excretion delay, Intrahepatic bile duct obstruction.