Mutations in human ether‐a‐go‐go‐related gene (hERG) can lead to type 2 long‐QT syndrome (LQT2). The authors previously identified the hERG mutation G604S results in a loss of function and obviously decreased current amplitude and impaired channel protein trafficking when co‐expressed with WT‐hERG. The present study further investigates the biological and electrophysiological consequences of pharmacologic chaperones in HEK293 cells expressing G604S‐hERG or co‐expressing G604S‐hERG and WT‐hERG. It was found that a low temperature (27°C), thapsigargin, NS1643 and E‐4031 fail to rescue the G604S mutation. Interestingly, only E‐4031 treatment resulted in a significant increase in hERG currents in cells co‐expressing G604S‐hERG and WT‐hERG, correspondingly more mature protein band at 155 kDa by Western blotting and an increased membrane staining by confocal microscopy. In addition, E‐4031 treatment shifted the steady‐state half maximal activation voltage (V1/2) of the inactivation curve by +8 mV in cells co‐expressing G604S‐hERG and WT‐hERG. The present experimental results suggest that a G604S mutation is resistant to pharmacological rescue. E‐4031 treatment resulted in a significant increase in hERG currents by promoting the hERG channel processing and trafficking in cells co‐expressing G604S‐hERG and WT‐hERG.