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Quantitative determination of albumin (ALB) in human urine is important to assess kidney functions in a variety of diseases. Recently, Siemens released an improved Microalbumin assay (microALB&#95;2) to measure urinary ALB on the automated, random access ADVIA 1650/1800, ADVIA 2400, and ADVIA 1200 Chemistry Systems. We evaluated analytical performances of this new method. All ADVIA Chemistry Systems use the same microalbumin reagent packs, microALB&#95;2 calibrators, and commercial controls. The within-run and total CVs of the improved method with two-level BioRad Liquichek Urine Chemistry controls (approximately 2 and 9 mg/dl ALB) and a urine pool (approximately 29 mg/dl ALB) on all ADVIA Chemistry systems were <4.1 and <6.1%, respectively (40 replicates per sample). The analytical range/linearity of the method (all ADVIA systems) was from 0.3 mg/dl to theALB concentration in the highest level of calibrator (approximately 38-42 mg/dl). The improved method (microALB&#95;2) on the ADVIA 1650/1800 (y) correlated well with both the Beckman DXC 800 Microalbumin and the old microalbumin method on the ADVIA 1650/1800 analyzers. The improved method showed <10% interference with 16 chemicals from acetaminophen to uric acid that may be present in urine. The improved method has a minimum of 60 days' on-system stability on all systems with the calibration frequencies of (with/without a Reagent Container insert) 20/30 days (ADVIA1200), 50/60 days (ADVIA1650/1800), and 20/60 days (ADVIA2400). No prozone was observed with the method on any platform up to the highest ALB concentration tested in a sample (4,000 mg/dl).