The role of toxic factors in the occurrence of end stage renal disease (ESRD) was demonstrated only in 2 to 10% of new dialysis patients, whereas hereditary factors were reported in 10-15% of patients. Hypothesis that at least 50% of patients with ESRD had renal disease due to environmental or occupational factors is probably true. However, responsible factors are difficult to identify and renal lesions are often unspecific. Rarely is only one risk factor responsible for the appearance of renal disease, and most often several environmental factors are implicated. Epidemiological methods to demonstrate the role of environmental or occupational factors in the occurrence of chronic renal failure (CRF) are not easy to use because at least two reasons. First is that the early diagnosis of CRF is difficult, because renal diseases are most often asymptomatic and depend on systematic measurement of plasma creatinine levels. The second reason concerns the choice of the epidemiological method to evaluate the suspected risk factor. In this review, P Simon discusses studies demonstrating the role of environmental or occupational factors in the appearance of CRF and the evolution to ESRD, particularly the responsibility of heavy metals (lead, cadmium, uranium, silicon, etc.), of solvents (halogenated hydrocarbons), of mycotoxins (ochratoxin A), of phytotoxins (aristolochic acid, cortinarius), and of some drugs (analgesic, lithium, cyclosporine, cis-platinum).