Small, forested streams rely heavily on allochthonous inputs of leaves and woody debris as a primary source of organic carbon. While breakdown rates in temperate streams have been well studied, little data is available for tropical streams, particularly in Africa. This study examined the breakdown rates in a tropical stream in Tanzania of four different species of riparian trees or shrubs. Leaf packs were assembled into sets of single species packs and tied to roots along the stream margins on July 15, 2006. Leaf packs were collected every 3 days for 21 days, after which very little material remained. Invertebrates on the leaf packs were identified, and the leaves were dried, weighed, and combusted. All four species broke down at different rates, with fast processing coefficients similar to those found in other tropical streams, with a range of 0.03 day-1 to 0.24 day-1. The breakdown rate of the largest leaf, Tabernaemontana pachysiphon, was significantly faster than the others. A concurrent study suggested crab preference for T. pachysiphon could contribute substantially to the high breakdown rate. These results indicated that leaf litter breakdown in tropical stream is rapid and associated with shredder activity.