SummaryRenal lymph protein concentration, intrarenal venous pressure (IRVP) capsular lymph pressure (LP) and tissue pressure (TP) were measured before, during and after short periods of renal artery occlusion. Pressure measurements were also monitored after experimentally elevating IRVP. Increases in interstitial protein concentration occur during renal artery occlusion and alter protein concentration in subesquent lymph samples without changing lymph flow. The recovery of TP and LP following renal artery obstruction appears to be secondary to the replacement of renal interstitial fluid volume until functional distention of the kidney is reached. Thereafter, TP and LP appear to be directly related to IRVP.