Urine albumin (Alb), total protein (TP) and creatinine (Cr) concentrations and the activities of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and gamma-glutamyl transpeptidase (GGT) were measured in untimed random urine samples from 157 non-insulin-dependent (NIDDM) diabetic subjects and 54 healthy subjects. In NIDDM subjects the excretions of TP, Alb, NAG, AAP, GGT (expressed in relation to creatinine) were significantly higher and were abnormal in 59.9%, 68.8%, 47.2%, 41.4% and 13.4% of the subjects, respectively. However, 24.5%, 22.4% and 6.1% of NIDDM subjects with normal Alb/Cr ratio had abnormal excretion of NAG, AAP and GGT, respectively. Alb/Cr ratio was greater than 26.8 mg/mmol (considered to be equivalent to albumin excretion of 250 mg/24 h) in 14.6% and between 2.5-26.8 mg/mmol (equivalent to albumin excretion rates of 20-250 mg/24 h) in 54.1% of subjects. In those diabetic subjects with clinical retinopathy only Alb/Cr ratio was higher. Arterial blood pressure was significantly correlated with Alb/Cr (r = 0.365) and NAG/Cr (r = 0.204). We conclude that prevalence of abnormal Alb/Cr is relatively common among Chinese NIDDM subjects.