Abstract We studied 23 long-term catheterized kidneys in 14 patients. The uptake ot 99mtechnetium dimercaptosuccinic acid ( 99mTc-DMSA) was measured at one- and two-hour intervals after injection, and the uptake was corrected for variations in renal depth. These values were compared with inulin, creatinine, and para-amino hippurate (PAH) clearances which were measured in each kidney by collecting urine through long-term catheterization. Correlation coefficient was obtained between PAH clearance corrected for the body surface area and the two-hour uptake of 99mTc-DMSA. The correlation coefficients between the two-hour uptake of 99mTc-DMSA and the clearance values are not significantly different from those between the one-hour uptake and the clearance values. Corrections of the uptake for variations in renal depth did not improve the correlation coefficients. The results show that 99mTc-DMSA is an excellent method to estimate the renal plasma flow and the one-hour uptake without correction for renal depth is clinically sufficient to evaluate the split renal function.