Аннотация:Variations of EUV-fluxes in four hydrogen lines of Lyman series and variations of the 10.7 cm radio flux (F10.7) which characterizes the level of solar activity were studied in cycles 23 –24. The relative changes in the yearly averaged intensity of these lines from the maximum to the minimum of 23 and 24 cycles were investigated. It was showed that maxima of fluxes in the lines and the half-widths of the line profiles in the maximum of activity cycles are greater than in the minimum. This indicates on different conditions of these lines’ formation in solar chromosphere.