Aims: The purpose of this study was to identify the effect of pentoxifylline on the urinary protein excretion profile in type 2 diabetic patients. Methods: 40 type 2 nonhypertensive diabetic patients were randomly allocated to receive either pentoxifylline 400 mg tid or placebo daily for 16 weeks. Eligible subjects were those with urinary albumin excretion between 20 and 200 μg/min. Subjects receiving angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium antagonists, and diuretics as well as those with reduced renal function, pregnancy, urinary tract infection, and smoking were not included. A 6-month pretreatment stabilization phase aimed to reduce and stabilize fasting serum glucose levels was carried out. Urinary proteins were identified by electrophoresis, and immunodetection was identified by Western blot. Electrophoretic analysis was performed using molecular weight markers of 150, 132, 77, and 66 kDa to identify high-weight proteins, and 54, 41, 36, 27, 21, 14.3, and 12 kDa to identify low-weight proteins. Results: At baseline, subjects in both groups who showed a glomerular tubular pattern did not differ in their urinary excretion profile. The urinary proteins identified were immunoglobulin G, ceruloplasmin, transferrin, and albumin (glomerular pattern) as well as α₁-antitrypsin, α₁-acid glycoprotein, collagenase inhibitor, α₁-microglobulin, trypsin inhibitor, lysozyme, and β₂-microglobulin (tubular pattern). Subjects who received pentoxifylline had reduced urinary excretion of high-and low-molecular weight proteins. Conclusions: Urinary protein excretion in type 2 diabetic subjects shows a mixed, glomerular and tubular, pattern. Pentoxifylline reduces the excretion of both high and low molecular-weight urinary proteins.