The purpose of this study was to establish the role of apoptosis in the developing renal corpuscle in the prenatal rat kidney. Kidneys from 14-, 16-, 18-, and 20-day-old fetuses[E-14, E-16, E-18, and E-20] were preserved by immersion or perfusion via the heart using Bouin`s fixative. Apoptosis was detected`by in situ nick end labeling method using ApopTag kit. In kidneys from E-14, apoptotic cells and bodies were found only in the mesenchymal tissue surrounding the developing nephrons. In kidneys from E-16, E-18, and E-20, apoptotic cells and bodies were located mainly in the columnar distal epithelium of the renal vesicle[future parietal epithelium] as well as in the parietal epithelium of the renal corpuscles of S-shaped bodies, stage III and IV nephrons. Apoptosis was not observed in the proximal part of renal vesicles or in the podocytes in renal corpuscles. In contrast, strong bel-2 immunoreactivity was present in the proximal part of the renal vesicle and in podocytes in S-shaped bodies, but gradually decreased in stage III and IV nephrons. The distal part of the renal vesicle had weak staining for bcl-2, and there was no bel-2 immunoreactivity in the parietal epithelium of S-shaped bodies, and stage III and IV nephrons. We conclude that bcl-2 is involved in the regulation of apoptosis during the differen-tiation of the parietal epithelium of Bowmann`s capsule.