Exciton states in semiconductor nanostructures with disorder exhibit level repulsion, a concept known from random matrix theory. Its manifestations in time-resolved Rayleigh spectra and in the autocorrelation of optical nearfield spectra are explained, and available experimental results are critically discussed. It is proposed to investigate the intrasubband absorption in quantum wells with emphasis on the aspects of level repulsion. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.