B.T.PABA has been evaluated as a new pancreatic exocrine function diagnostant. In this study, it was used as a new absorption test. After ingestion of 1 gm of B.T.PABA and the test meal, PABA in 6-h collected urine was determined. The urinary PABA excretion rate in Billroth I type postgastrectomy patients, 8-14 days after surgery, was lower than that of controls and that in Billroth II patients, 10-14 days after surgery, was the lowest of the three. However, the PABA excretion values of postgastrectomy patients 10 months to 20 years after surgery recovered nearly to the normal level of PABA excretion. These decreases in PABA excretion were considered to be caused by postgastrectomy digestion-absorption impairment. In addition, there was a significantly high correlation between the conventional 131I-labeled albumin absorption test and the B.T.PABA test. Therefore, it was concluded that the B.T.PABA test can be used as a simple absorption test.