The rain forests of Tanzania occupy small areas, mostly confined to isolated mountains. Except for some isolated volcanic mountains (Mt. Kilimanjaro, Mt. Meru, the Ngorongoro Crater), most of the rain forests are confined to the so-called Eastern Arc mountains with old crystalline bedrocks. The Eastern Arc rain forests are characterized by high biodiversity, and have large numbers of endemic and rare taxa of plants and animals. The submontane and montane rain forests are extremely important water catchments, providing water for major cities and densely populated rural areas. Most of the rain forest catchments are forest reserves, but still the human impact around and inside the reserves is considerable. Intensive cultivation due to heavy population pressure affects the reserves from all sides, leaving the forests isolated, fragmented ‘islands’ surrounded by the cultural landscape. Former timber production and logging programs initiated by the State and some foreign development organizations have depleted large areas of rain forests, e.g. in the Usambara Mountains. Extensive, destructive, legal and illegal activities such as, e.g. logging, pit-sawing and grazing have taken place inside most of the forest reserves. Some research programs on rain forest catchments are now being carried out in Tanzania, forming a basis for future management and monitoring of the forest reserves. The forest authorities are currently much concerned about the problems, giving catchment forest management highest priority in the Tropical Forestry Action Plan.