The analysis of fluorescent characteristics and degree of molecular association of three fluorescent nanomarkers (eosin, erythrosin and fluorescein) in solutions of human serum albumin (HSA) at different pHs is made. The common features for all three nanomarkers under influence of bionanomolecules of HSA are the quenching of the fluorescence, the red shift of maximum of fluorescence and the decrease of degree of molecular association for every fixed value of pH. The differences in dependences of fluorescence and degree of molecular association on pH between fluorescein and its halogen - derivatives (eosin and erythrosin) are registered. It is established that the quenching of fluorescence by HSA is of compound statically-dynamical type. The electronegativity of lateral atoms in Structural formulas of nanomarkers forms the basis of explanation of all features of experimental data in the system "fluorescent nanomarker - protein - buffer solution". (C) 2008 Elsevier B.V. All rights reserved.