In order to assess the plasma amino acid pattern in nephrotics, we studied 19 nephrotic patients in good general and nutritional conditions. The results were compared with those of 8 healthy controls of matched age and sex. A highly significant rise of plasma glutamic acid and hydroxyproline was detected in nephrotics. When the latter group is divided into 2 subgroups according to the serum creatinine level, the rise in plasma values of both amino acids was detected in both subgroups compared to the controls, while an insignificant rise was detected in cases with elevated serum creatinine compared to those with normal serum level. So we conclude that there is an alteration in the amino acid pattern in nephrotics, and that this alteration occurs early, before the rise in serum creatinine.