  Results of a long-term monitoring ($\gtrsim 10$ years) of the broad line and
continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and
NGC 5548, are presented. We analyze the H$\alpha$ and H$\beta$ profile
variations during the monitoring period and study different details (as bumps,
absorption bands) which can indicate structural changes in the Broad Line
Region (BLR). The BLR dimensions are estimated using the time lags between the
continuum and the broad lines flux variations. We find that in the case of 3C
390.3 and NGC 5548 a disk geometry can explain both the broad line profiles and
their flux variations, while the BLR of NGC 4151 seems more complex and is
probably composed of two or three kinematically different regions.
