It was observed in patients with renal disease or hepatitis that the activity of urinary transaminase was high. In former, urinary transaminase increased with the exacerbation of the disease and with high proteinuria, but it had no relation with serum transaminase. In latter, the transaminase activity of urine increased with that of serum. GPT is somewhat resistant for heating in comparison with GOT, but for treatment with tryprin and lipase, GPT is more labile than GOT. The transaminase was found in β-globulin fraction of urinary protein and it is supposed that the transaminase in urine comes from the serum. An experiment in Masugi's nephritis of rabbit showed that the urinary transaminase activity increased with the rise of urinary protein, but that of serum was normal.