Aims: The HERG (erg1a) channel has been shown to exhibit a strong temperature dependence resulting in higher current amplitudes at physiological temperature compared to room temperature. Nevertheless native erg channels often comprise heteromeric channels involving erg1a/1b (e.g. in the heart) or also erg2 and erg3 (e.g. in the brain). The present study presents data on the temperature dependence of erg1a/1b and erg3 channels. Methods: CHO cells were injected with rat erg1a and erg1b cDNA (ratio 1:1) or with rat erg3 cDNA, and erg currents were recorded with the patch-clamp technique in the conventional whole-cell configuration. Bath temperature was set to near physiological values (35°C) or room temperature (21°C). Results: For heteromeric erg1a/1b channels, the voltage dependence of activation was shifted to more negative potentials at elevated temperature compared to room temperature. Gating kinetics were considerably faster, with activation and revovery from inactivation being more temperature sensitive than inactivation and deactivation. Steady state current amplitudes were significantly higher at physiological temperature. In contrast, the voltage dependence of activation of erg3 channels was shifted to more depolarized potentials at elevated temperature and the kinetics for recovery from inactivation and for deactivation exhibited a similar temperature sensitivity. Steady state current amplitudes were also increased at higher temperature. Conclusion: Comparison with published data suggests a similar strong temperature sensitivity of heteromeric erg1a/1b channels as described for homomeric erg1a (HERG) channels. In contrast, changes in temperature affect the biophysical properties of erg3 channels in a different way. These results show that data obtained for erg1a cannot be transferred without modifications to other erg family members or to native heteromeric erg channels.