We have studied the rat remnant kidney model as a tool to assess the impact of secondary oxalosis on renal failure. Although the plasma of uremic rats demonstrated increased levels of oxalic acid, deposits of oxalate crystals in tissue were not observed. The absence of such deposits in the remnant kidney, as well as other tissues, may be due to a lesser degree of hyperoxalemia observed in the rat compared to man or may reflect that uremic deaths among the experimental animals occurred prior to formation of detectable calcium oxalate deposition. We conclude that the rat remnant kidney is not a suitable model to study the impact of uremic oxalosis in man.