Studies of characteristics and properties of dissolved organic matter (DOM), its fluorescent fractions (FDOM) in waters of Yenisei and Angara rivers are presented. The studies have been carried out by measuring spectral absorption coefficients (in the spectral range from 400 to 800 nm), as well as the intensity of DOM fluorescence at three wavelengths (505, 525, and 540 nm) excited by radiation at 390 nm. The following parameters were used: coefficients characterizing the slopes of the spectral distribution of light absorption and DOM fluorescence, specific absorption coefficients of DOM and FDOM at the wavelength of radiation exciting the fluorescence (κsp, κf.sp), energy and quantum yields of DOM and its fluorescent fraction, and specific fluorescence of DOM and FDOM. The fraction of FDOM in the total DOM varies, in waters studied, from 8 to 40% with the mean value being about 19%. The quantum yield varies from 0.18 to 0.40 (the average value is 0.28). Specific absorption coefficients of DOM and FDOM are on the average close to each other (κf.sp/κsp makes 0.93).