An urea transporter (UT) cDNA fragment, sharing high identity with rabbit, rat and human UTA2, was cloned by RT-PCR from papilla and upper pelvic epithelium of sheep kidney. Quantitative RT-PCR after low protein diets disclosed, compared to normal protein fed sheep, a significant reduction in UT mRNA levels in pelvic epithelium (852±172 vs 2024±260 molecules; P<0.01) and a tendency to its increase in papilla (7959±1741 vs 5447±1040 molecules; NS). The reduction of UT expression in the upper pelvic epithelium could be relevant for the renal urea conservation in protein-restricted sheep.