This chapter describes the composition of the macroinvertebrate fauna of tropical streams, especially the insects, with the aim of uncovering the patterns in diversity and richness that they exhibit. It reveals that insects and other tropical macroinvertebrates are sometimes affected by temperature, but that flow regime and habitat stability have a primary influence on life. -history parameters and population dynamics. Decapods make an important contribution to overall production in some tropical streams, and may offset low production by insects. "Macroinvertebrates" are those invertebrates exceeding 0.5 mm body size, or large enough to be seen by the naked eye, and comprise mostly insects as well as decapod crustaceans, mollusks, leeches, oligochaetes, and planarians. The none -insect groups are dominated by turbellarian Planariidae, mollusks, and crustaceans. It shows that most studies of the life. -history attributes of macroinvertebrates in tropical streams concern the temporal components of voltinism and phenology and most have concerned insects. Macroinvertebrate secondary production estimates integrate information on population dynamics and energy flow that are of considerable ecological importance. One obvious gap in studies of macroinvertebrate lifehistories is uncertainty about fate and behavior of adult aquatic insects in the tropics. It highlights that the amounts of research devoted to macroinvertebrates in tropical Africa is much less than elsewhere in the tropics, yet the threats that streams in this region face are no less than those in the rest of the tropics.