The results of U-filter flare monitoring of the binary flare star FL Vir = Wolf 424 is presented. 57 flares with energies between 2x10^28^ and 2x10^31^erg were recorded in 20h of observation. The properties of flare occurrence and flare time-scales are analysed, and the flare activity level in 1980 April is determined to be L_f_(U)=8.0x10^26^erg/s. This is larger than previously published results and may indicate a variation in the flare activity level on a time-scale of years. An analysis of existing data indicates that the flare activity level correlates with the relative orbital positions of the stars.