Cyg X-3 . We carried out a monitoring program to study the flare variability of the radio emission of X-ray sources. ... After this flare, there was a sharp decrease in the radio intensity on May 29--31, to 15--20 mJy at 4--11 GHz, 10--12 days before a powerful flare on June 12 (~4 Jy). ... We found the signifficant correlation of the radio flux and hard X-ray (BATSE data) radiation and anti-correlation of the radio flux and soft X-ray (RXTE ASM data) radiation during the powerful flare. ...