Su rn rnaryBrugia malayi-infected patients, endemic normals with high levels of specific antibodies and European controls were investigated for kidney disorders by noninvasive techniques. Groups of patients with filarial infections included asymptomatic, microfilaraemic cases (group I ) , patients with filarial fever (group 2) and with obstructive filariasis (group 3). Several patients underwent a treatment course with diethylcarbamazine (DEC) when blood and urine samples were collected. Urine samples were investigated for proteinuria and analysed by SDS-PAGE to discriminate between proteinurias caused by tubular and glomerular disorders. In addition, urine levels of a-I microglobulin, of the brush border antigen gp400 and of N-acetyl-P-glucosaminidase (NAG) activity were determined as indicators of tubular disorders, the albumin content of the urines served as indicator of glomerular alterations. IgG rheuma factors were also decermined in the serum as possible reasons for glomerulonephritis. Neither in the endemic normals nor in the European controls there was evidence for kidney disorders. Infected patients had significantly increased proteinuria compared to controls. There were no significant differences between the 3 groups of infected persons, although the mean protein levels were highest in cases with chronic disease and lowest in asymptomatic patients. Quantitative urine analyses and results of accompanying tests suggest predominantly tubular but generally relatively weak disorders in asymptomatic infections; abundant involvement of the kidney which involves both compartments of the organ in the course of filarial fever; and partly severe and probably chronically progredient kidney alterations, which predominantly affect the glomerula in symptomatic cases. IgC rheunia factors d o not seem to play a role in filarial infection associated renal disease. DEC-treatment indeed did not significantly alter degree and character of the proteinuria, bur relativcly high albumin levels in the urine of treated persons yet suggest increased glomerular disorders in these cases. In conclusion, renal disease appears to be a common event in Brugia filariasis; involving both the tubular and glomerular compartment of the organ its pathogenesis is obviously complex and not only immune complex-mediated.keywords Lymphatic filariasis; Brugia malayi; renal disease; tubular disorders; glomerulonephritis, DEC; noninvasive diagnostic techniques for kidney disorders correspondence Prof.