Heating of a single-electron transistor (SET) caused by the current fl
owing through it is considered. The current and the temperature increa
se should be calculated self-consistently taking into account various
paths of the heat drain. Even if there is no heat drain from the centr
al electrode of the SET due to transfer of phonons, the temperature of
this electrode remains finite because electron tunneling decreases th
e temperature difference between the central and outer electrodes. Ove
rheating effects can cause hysteresis in the I-V curve of the SET in t
he vicinity of the Coulomb blockade threshold.