Kidneys of patients on hemodialysis therapy often undergo structural changes leading to acquired cystic disease. A wide variety of chemical compounds are known to induce experimental renal cystic disease. Since aluminum intoxication has been implicated in the development of encephalopathy, osteomalacia and anemia in uremic patients, this study was designed to investigate whether aluminum administration to normal rats could induce renal morphological changes. Male Wistar rats were divided into three groups; Animals of the Low-dose aluminum (LDA) group received 0.2 mg/day of aluminum, animals of the high-dose aluminum (HDA) group received 2 mg/day of aluminum; the third group consisted of controls (C). Aluminum was injected intraperitoneally as aluminum chloride (6 days a week). 13 weeks later, the kidneys were removed and examined by light and electron microscopy. The findings on eight-microscopic examination were normal in all groups. Electron-microscopic examination was unremarkable in the C and LDA group. In HDA rats, ultrasections of the cortex and outer medulla showed changes in the proximal tubules with increased size and number of lysosomes, osmiophilic granular material inside the lysosomes, vacuolisation of organelles and mitochondrial damage of varying degree. No cystic changes were found.