The uptake efficiency of fluorescent brightening agents (FBAs) built in detergents onto household textile materials in practical washing under controlled conditions of multicycle bundle testing and coin laundry testing were investigated. Quantitative determination of the FBAs in residual liquor of sudsing and rinsing baths after washing were performed by fluorometric analysis and high performance liquid chromatography. Following results were obtained : 1) The average of the discharge ratio of FBA reaches a steady state of about 50% after 8 cycles of washing, although it is about 90% at 1-2 cycles. 2) The discharge ratio of FBAs in the coin laundry testing differs from the type of washing machines. 3) The discharge ratio of FBAs depends on the type of FBAs built in a commercial detergent. 4) The uptake efficiency of FBAs built in commercial detergent on practical washing is estimated to be about 50% of the applied FBAs.