The geomorphoclimatic theory is used, along with the joint probability density function of storm duration and storm intensity and the representation of the infiltration process, to derive the flood frequency distribution for a given catchment. The infiltration process is represented by two different approaches: a simple time averaged potential infiltration rate and a more realistic model based on Philip's infiltration equation. The resulting flood frequency distributions are in analytical form, containing only few climatologic and physiographic parameters of the catchment. These frequency distributions are tested against historic records from arid and wet climates with very satisfactory results. They will be very valuable in the design of flood control systems since they provide a theoretical basis for estimating flood frequencies in the absence of stream flow records. A 37-item bibliography (1945-82) is attached. (Author abstract).