Tubuloglomerular feedback responses were examined in control euvolemic and glomerulonephritic rats 4 wk after administration of antiglomerular basement membrane antibody (AGBM). Single-nephron glomerular filtration rate (SNGFR) was reduced approximately 30% in AGBM rats. Tubuloglomerular feedback responses were also tested with both artificial and native tubular fluid. SNGFR was evaluated at 0, 10, 20, 30, and 40 nl/min. Tubuloglomerular feedback response was present in both control and AGBM rats, although there was a shift in turning point or perfusion rate down and leftward at which SNGFR decreased in the AGBM rats. No difference in tubuloglomerular feedback responses was observed between artificial and native tubular fluids. In this model of moderate glomerulonephritis, tubuloglomerular feedback activity appears to be appropriate and intact, and the composition of the fluid entering the loop of Henle does not appear to determine or to be a condition for the presence or absence of tubuloglomerular feedback activity.