The present study was undertaken to determine the usefulness of a new, sensitive urinary dipstick, Micral-Test II (Boehringer-Mannheim, Mannheim, Germany) for the detection of microalbuminuria (urinary albumin concentration: 20-200 mg/l) in diabetic patients. four hundred and eleven consecutive outpatients with diabetes were screened for microalbuminuria. The diagnostic accuracy of Micral-Test II for the detection of urinary albumin excretion > 20 mg/l was assessed by comparing the urinary albumin concentration determined by Micral-Test II with radioimmunoassay (RIA). In comparison with radioimmunoassay, Micral-Test II had an overall sensitivity of 93%, specificity of 93% and positive predictive value of 89%. False negative results were found in 7% and false positives were obtained in 7% of specimens. These findings suggest that Micral-Test II may be a useful method for the screening of microalbuminuria. However, it should not be regarded as a diagnostic test and a positive result should be followed by measuring AER by a laboratory based method.