We report on characterisation of the effect of femtosecond laser pulse illumination on photoluminescence (PL) properties of CdSe nanocrystalline films (diameter approx. 5 nm) prepared by chemical bath deposition technique on crystalline silicon substrate. The substantial PL efficiency enhancement (up to 20X) and modification of PL spectrum were dependent on ambient atmosphere and illumination intensity. We discuss the possible microscopic origin of the observed effect and we suggest the rate equation model to reproduce the experimental data. (C) 2003 Elsevier B.V. All rights reserved.