Recent excavation of a series of Late Pleistocene cave deposits at Klasies River Mouth, situated on the Tsitsikamma coast in the southern Cape, has been directed towards a detailed understanding of environments during the last interglacial-glacial cycle. Particular attention is being focussed on the effects of climatic change on the productivity and diversity in plant and animal communities and ultimately on the distribution and relative abundance of human populations. Fossil materials, notably marine and terrestrial invertebrates as well as micro- and macrovertebrates introduced by man and other agents provide a rich source of palaeoecological data. The problem of dating the Late Pleistocene cave deposits is being approached by electron spin resonance, ionium and other analyses. A regression noted within the Cave 1A sequence coincides with part of the Howiesons Poort substage of the Middle Stone Age.