HBsAg. was identified in the urine of the patients positive for serum HBsAg. by Tripatzis in 1970. In 1977, Hourani et al reported the incidence of HBsAg. in urine was about 52% in the patients positive for serum HBsAg. with hemodialysis treatment due to chronic renal failure. A series of studies on the HBsAg. in urine has revealed the urine of the patients positive for serum HBsAg. to be important source of infection. But there's much room to debate on the relationship of HBsAg. in urine with infectivity and the exact mechanism of urinary emergence of HBsAg. The authors detected HBsAg. in serum and urine by employing sandwitch solid-phase radioimmunoassay, and performed urinalysis, liver function test and renal function evaluation. Percutanous liver and/or kidney biopsis were done. Among 38 renal disease patients, 9 cases(23.4%) were shown to be positive for serum HBsAg. and 5 cases(55.5%) among above 9 patients positive for urine HBsAg. 56 cases(67.4%) of 83 liver disease patients revealed positive for serum HBsAg. All 10 renal and liver disease patients revealed positive serum HBsAg., and among the 9 cases(90%) positive for urine HBsAg. In the 25 patients positive for urine HBsAg. all of 5 renal patients and 9 renal and liver patients had hematuria or/and proteinuria above 2 positive for albumin. But in the 11 liver patients 6 cases(55.1%) were normal findings. And there's no significant in cpm of urine HBsAg. between the patient positive for serum HBsAg. and negative, and in cpm of serum HBsAg. between liver and renal disease patients. But there's statistical significance in cm of urine HBsAg. between renal and liver diseases.