This paper discusses several tests that may permit the early detection of renal changes induced by long-term exposure to nephrotoxic industrial chemicals and may possibly serve as advance warning of pending renal damage. Some tests mainly attempt to assess the integrity of the glomerulus: high molecular weight proteinuria, glomerular basement membrane (GBM) antigens in blood and in urine, circulating anti-GBM antibodies, glomerular filtration rate after an acute oral load of proteins, and estimation of membrane negative charges (ie, glomerular polyanion). Others mainly attempt to identify functional and/or morphological changes at the tubular level: low molecular weight proteinuria, aminoaciduria, glucosuria, hyperphosphaturia, hypercalciuria, enzymuria, tubular antigen excretion, kallikrein, and prostaglandin excretion. Some of these tests are already routinely used, although controversy may still persist with regard to their clinical significance. Recently, new tests have been developed that may open new perspectives for assessing the significance of the early renal changes induced by chemicals.