Most of our present-day knowledge of the photometric behaviour of Be stars still comes from various surveys only. Little attention was paid to systematic studies of possible photometric variability of particular objects on different time scales. Nevertheless, just this kind of information is necessary if one wants to study the physical relationship and/or differences between Be stars and other types of B stars like Beta Cepheids, supergiants, helium-rich stars etc., and to test various models of the Be phenomenon. Long systematic photoelectric observations do exist only for several Be stars. They invariably indicate that the long-term variability - if present - is always the most pronounced one. In some cases, this long-term variability masks the periodic light variations occuring on shorter time scales (see, e.g., the case of CX Dra, Koubský et al 1980).