The effect of various nonpolar and polar solvents on the location of absorption and fluorescence of Nile Red at room temperature was investigated. Based on the batochromic shift of electronic spectra of Nile Red and Bilot-Kawski theory the following values of ground- and excited-state dipole moments mu g = 8.2 +/- 1.0 D and mu e = 10.0 +/-1.0 D were found. The reasons of high discrepancy between the literature results were discussed. (C) 2008 Elsevier B. V. All rights reserved.