3-Bromobenzanthrone (3-BBA) is an anthraquinone dye intermediate widely used for the synthesis of a variety of dyes. The monitoring of 3-BBA exposure in dyestuff industry workers has not been possible until now as no procedure has been available. In this article, the fluorescence properties of 3-BBA has been utilized to develop a quantitative method for the detection of this dye intermediate. The procedure allows the measurement of trace quantities of 3-BBA in biological specimens, including urine, serum, liver, and feces, in experimental studies. The method involves extraction of biological samples with an equal volume of a chloroform-methanol mixture (1:1, v/v) followed by measurement of the relative fluorescence intensity at excitation maxima of 400 nm and emission maxima of 530 nm. The detection limit was found to be as low as 50 ng of 3-BBA. The procedure can be routinely used to screen for the presence of 3-BBA in biological fluids, especially urine, as a measure of exposure to 3-BBA in dyestuff workers. The authors are thankful to Dr. P. K. Seth, Director, Industrial Toxicology Research Centre, for his keen interest in this study. The secretarial assistance of Mr. K. G. Thomas is duly acknowledged. RPS is thankful to University Grant Commission, New Delhi, for the award of a Senior Research Fellowship.