Direct observation of large permanent dipole moments of excitonic complexes in InGaN/GaN quantum dots is reported. Characteristic traces of spectral diffusion, observed in cathodoluminescence of InGaN/GaN quantum dots, allow deducing the magnitude of the intrinsic dipole moment. Our experimental results are in good agreement with realistic calculations of quantum dot transition energies for position-dependent external electric fields. (C) 2010 American Institute of Physics. [doi:10.1063/1.3477952]