This review has been prepared for the international seminar: Rain fall as the basis for urban runoff design and analysis, held in Copenhagen, 24926 Aug. 1983. The purpose of the review is to bring a state of the art within, 1) the statistical characterization of rain fall in time and space, 2) the development of synthetic design storms and, 3) the application of both synthetic design storms and historical storms to pipe design, flooding prediction, design of detention basins and calculation of the yearly or extreme pollutiona1 load on receiving waters from combined sewer overflows. The main conclusion, primarily related to item 3), is that more attention in this context should be put on statistical analysis of the detrimental effects: flooding and pollution. This analysis is best performed by applying historical rain records. Realistic flooding prediction is believed only to be possible with a fully dynamic flow model, whereas pollution may be studied by means of simpler models like the time area approach. The outstanding problem in the statistical prediction is the distribution in space of the historical rains.