The African Great Lakes differ from shallower large African lakes by undergoing seasonal stratification and from large reservoirs in having long residence times, so that the ionic concentration of the lake water differs substantially from that of the inflows. The African Great Lakes are so large that limnological events are usually local, causing regional differences. They can he regarded as models for oceanic systems, with local processes playing a major part in nutrient cycling, Production, on an area basis, may be high because of the considerable depth of the euphotic zones of many of the lakes, but the production cycle is poorly understood because of temporal and spatial limitations of sampling. Cyclonic upwelling may play an important part in offshore nutrient cycling. Links between limnology and fisheries are becoming apparent. Catches of Oreochromis in Lake Malawi are correlated with falling lake levels three years previously, which is explained in climatological terms. Different transfer efficiencies between plankton and fish production may reflect differences in the depth of the euphotic zone. The history and seasonal changes in deep stratification appears to have had a large influences in the evolution of demersal fish faunas. The lakes are so large and so complex that their complete investigation is beyond the resources of any single Government. There is a need for independently funded fundamental research to complement the applied research which must be the first priority of local Governments. Keywords: African Great Lakes, definition, limnology, internal regional variation, water budgets, plankton, fisheries, Namib, water, expeditions, desert research.