We present some results of multiband study of variability of a bright blazars sample. The collaborative studies using optical and radio telescopes of Special Astrophysical Observatory
of the Russian Academy of Sciences (SAO RAS), Crimean Astrophysical Observatory (CrAO RAS) and Institute of Applied Astronomy (IAA RAS) revealed numerous manifestations of flux
variation on various timescales: from hours to years. The radio data are represented by the 1–22 GHz measurements from the SAO RAS RATAN-600 radio telescope, the 5 and 8 GHz data from the IAA RAS RT-32 telescopes, and the 37 GHz data from the RT-22 telescope of CrAO RAS. The optical measurements in the 𝑅-band were collected with the SAO RAS 1-m Zeiss-1000 and 0.5-m AS-500/2 telescopes. Additionally we used the archive data at 230 GHz from the Submillimeter Array (SMA) and the 𝛾-ray data in the 0.1–100 GeV band from the Fermi-LAT point source 4FGL-DR2 catalogue. A significant correlation between the radio, optical, and 𝛾-ray bands is found for all presented blazars. The discovered properties of multi wavelength variability suggest
that the mechanisms dominating the radio–𝛾-ray variations are not substantially different. The detected quasi-periodic oscillations for blazars AO 0235+164 and Ton 599 of are tentative, as the
time span of the observations includes fewer than 3-4 full cycles for all the data sets. These results as well as hypothesis about double supermassive black holes in their centres should be interpreted with caution, given the limited number of observed cycles and the influence of red noise.