This contribution deals with the application of population balances in the chemical industry for the modelling of dispersed phase systems. Two examples involving industrial production processes are presented. The first example concerns the investigation of sustained oscillations occurring in a production scale crystallizer equipped with an external fines dissolution loop. For this example it will be shown, that population balance-based models can be used to analyse and overcome such oscillations. The second example describes questions occurring in the design and the operation of a solids production process. To investigate these questions, population balance-based models in connection with flow sheet simulation techniques can be used. In the second part of this contribution future needs for a more routine application of population balances are identified from an industrial point of view. (c) 2005 Elsevier Ltd. All rights reserved.