  RU Peg is a dwarf nova (DN) of the U Gem type. Our analysis of its long-term
optical activity uses the data from the AAVSO database. It concentrates on
investigating the properties of the individual outbursts and the time evolution
of the ensemble of these events. No significant irradiation of the disc by the
white dwarf was detected. In the interpretation, a variable steepness of the
rising branches of the individual outbursts shows that the start of outbursts
of RU Peg can occur at various distances from the disc centre without
remarkable changes of the outburst recurrence time $T_{\rm C}$. The disc
overflow of the inflowing mass stream, varying with time, could contribute to
the changes in the starting position of the heating front, hence the variations
of the outburst types. A typical length of $T_{\rm C}$ was 90 days. The
segments of the relatively stable length of $T_{\rm C}$ were accompanied by the
primarily little variable and small values of the fluence (the energy radiated
in the optical band in the individual outbursts). Jumps of $T_{\rm C}$,
accompanied by the big scatter of the fluences, sometimes replaced them. In the
interpretation, a combination of variations of $T_{\rm C}$ with the unstable
properties of the outbursts, including an unstable mass transfer rate between
the components, shows the influence of several mechanisms on the state of the
disc in various time segments.
