Marine botanical research activities in the Western Indian Ocean region have increased significantly over the past two decades, contributing to a growing awareness and enhanced understanding of the important values and functions of the main primary producers in the coastal ecosystems of this region (UNEP 1982). Whereas a major proportion of the research has been descriptive, focusing on the distribution and general biology of mangrove, seaweed and seagrass plants and microalgae, more recent research has diversified its attention to include various other more quantitative and applied research topics (Björk et al. 1996). Throughout the region, increasing efforts are underway for coastal zone management, mangrove rehabilitation and marine conservation (e.g. Tanzania Coastal Management Partnership 1999), which call for a solid scientific knowledge base. Yet, new research initiated without a thorough review of past and recent research outputs may lead to a deficiency in the relevance of the knowledge being produced (Hatcher et al. 1989). The present review of the current status of marine botanical research (1950–2000) in the Eastern African region was made to provide a diagnosis of its strengths and weaknesses, with the aim of identifying the main research challenges to be faced to assist in the development of a solid basis for the management, conservation and wise use of the marine botanical resources in this region.