Tests of renal function that may be used to detect nephrotoxicity in workers are reviewed. Only tests potentially useful in cross sectional epidemiological studies of occupational populations are examined. Most renal results can be categorized as to whether they involve primarily the glomerulus, the renal proximal tubules, the distal tubules, the interstitium, or the renal vasculature. A list is given of toxic responses of these target tissues associated with a variety of toxic occupational or environmental exposures. Tests commonly used to detect glomerular dysfunction are listed and discussed. Although there are obvious limitations to using serum markers to detect reduced glomerular function, finding alternatives is more difficult. Detecting glomerular dysfunction by protein in the urine is also common, but decisions must be made concerning the probable source of proteinuria, the sampling schedule, and the degree of quantitation needed, each of which is discussed. Tests of proximal tubular injury are listed and described. Techniques for fractionating proteins in urine are discussed. It is noted that relatively fewer measures are available in field settings to detect distal tubular dysfunction. Measurements of renal concentrating ability and urine acidification are listed and described. Microscopic examination of the urine sediment is discussed, although logistical difficulties are described which have prevented quantitative microscopy from becoming an integral component of field studies. Problems in the choice of units for expressing excretion of substances in the urine and appropriate techniques for preserving urine samples to prevent degradation of the substances of interest are briefly considered. The authors conclude that given the present state of the art, the choice of test for a given setting rests upon considerations of feasibility and on the type of pathology expected from the agent under study. Studies are needed to evaluate these screening tests to determine sensitivity, specificity, and predictive power.