We report on a correlation between the gate leakage currents and the drain current collapse of GaN/AlGaN/GaN high electron mobility transistors. Unpassivated devices on intentionally undoped and doped (Si, 5×1018 cm-3) heterostructures were investigated. We observed in the devices that the larger the gate leakage current, the smaller the drain current collapse measured at 50 ns gate-voltage pulse turn on, and this correlation is independent of the doping of the structure. The correlation holds for two orders of magnitude in the gate-leakage current and up to 15% in drain current collapse. We believe that the leakage current can modulate trapped surface charge so that the time constant of the current collapse becomes much faster and dependent on the amount of leakage current itself.