A procedure is developed for estimation of human blood serum albumin in hyperbilirubinemia using a fluorescent probe 9,10-dianiline-2-sulfoanthracene (K-33). Use of the probe N-phenyl-I-amino-8-sulfonaphthalene (ANS) led to underestimation of albumin in hyperbilirubinemia as bilirubin and other inhibitors prevented the ANS binding with blood serum albumin. Substitution of ANS for K-33 enabled to estimate the albumin concentration under conditions of the pathology accompanied by an increase of endogenous ligands content in blood serum. The rate of K-33 (15 mM) fluorescence in blood serum (diluted 400-fold, at pH 4.0) correlated with albumin concentration (r-0.955).