Maintenance of serum albumin levels within normal limits is difficult to achieve in nephrotic children with normal renal functions who are unresponsive to specific treatment. One approach in such children is unilateral nephrectomy with rapid progression to renal failure. Peritoneal membrane is permeable to fluids, electrolytes and proteins, and peritoneal space has been used for total parenteral alimentation. Experimental ureteroperitoneostomy has been reported not to cause any significant side effect. The aim of this study was to evaluate the effects of unilateral ureteroperitoneostomy on serum and urine protein levels in rats with adriamycin-induced nephrosis. Adriamycin nephrosis was induced in 45 male Wistar rats. After two weeks, unilateral nephrectomy (Nx), unilateral ureteroperitoneostomy (Up) and sham operated (Sh) groups, each including 15 rats were formed. Serum creatine (S(Cr)) and albumin (S(alb)), and daily urinary protein excretion (U(pro)) were determined before adriamycin injection (week 0), before operations (week 2) and at the end of 6th week in all rats. In addition, percent change in serum albumin (deltaS(alb)) and urine protein levels (deltaU(pro)) between weeks 0-2, 0-6 and 2-6 were calculated for each group (e.g.; deltaS(alb) 0-2 = [S(alb) week 2-S(alb) week 0]/S(alb) week 0 x 100). Then, these parameters were compared within and between the groups. Furthermore, peritoneal tissue samples were obtained from the rats in Sh and Up groups to be examined for pathological changes. S(Cr) did not change within and in between the groups during the study period. S(alb) decreased significantly at weeks 2 and 6 with respect to week 0 in all three groups. In addition, although S(alb) tended to decrease at week 6 with respect to week 2 in all groups, this was significant only in Sh group. U(pro) increased significantly at weeks 2 and 6 with respect to week 0, and at week 6 with respect to week 2 in all groups. However, S(alb) and U(pro) were not different between the three groups at weeks 0.2 and 6. On the other hand, deltaS(alb) and deltaU(pro) were not different between Sh vs. Nx and Nx vs. Up rats, but deltaS(alb) 0-6, deltaS(alb) 2-6 and deltaU(pro) 0-6 were significantly lower in Up group compared to Sh group. Histopathological examination of peritoneal samples revealed significantly higher fibrosis score in Up group compared to Sh group. In conclusion, unilateral ureteroperitoneostomy may one important therapeutic selection in the treatment of intractable nephrotic syndrome. However, peritoneal fibrosis could be a concern for further use of peritoneum in case of end stage renal failure.