Abstract: A simple, rapid and sensitive laser time-resolved fluoroimmunoassay foralbumin in urine is developed. The assay is based on the competition between Tb-labeled albumin and the albumin in the sample or standard for the limited amountof rabbit anti-human albumin antibody. After the immunoreaction, the boundfraction of Tb-label is redissolved in the solution containing Tiron, convertedinto a highly fluorescent chelate, and measured in a timeresolved fluorometer witha small sealed nitrogen laser as the pulsed excitation source. The concentrationrange of the assay for albumin in urine is from 1 to 225 mg/l. The assay can beperformed within 2 h.