We have presented new data from the optical monitoring of 22 
-ray loud
blazars included in the Torino observational program. Most of the sources
showed a more or less pronounced variability; some of them (PKS
0420-01, OJ 248, 4C 29.45, PKS 1510-08) revealed an intense
activity. In general, the patterns of the light curves in different bands
are similar; however, in a few cases (PKS 0422+00, 4C 29.45, 3C 454.3)
colour changes were observed. The results of intranight observations of 3C
66A and OJ 287 have also been presented, showing microvariability.
Although the time coverage of our light curves is satisfactory for most
sources, we recognize the importance of collecting data from many observatories
in order to have a better understanding of the flux behaviour. This is
especially needed when the observational data are used as a test for the
theoretical models. In particular, a complete picture requires to know possible
correlations between fluxes at different wavelengths. In this sense we expect
that our data contribute to clarify the mechanism responsible for the
-ray emission, when a comparison with the data taken by EGRET in the
same period will be possible.