Abstract: Colonization of submerged artificial substrates by macrobenthic invertebrates in Ogba River Benin City, Nigeria was examined. Investigation involves the use of local traps over an exposure periods of 4, 10, 21 and 40 days. 1074 benthic organisms were recorded of which the weeds and plant stems substrates recorded density of 61.64 and 38.36%, respectively. Thirty-two macro-invertebrate taxa were recorded. The dominant groups were Ologochaeta and Diptera. Colonization of the substrates occurred at different rates. Early colonizers include the families Chironomidae, Naididae and Bufanidae in the 4 and 10 days exposure periods, while the late colonizers were mollusc and crustacean in the 21 and 40 days experiments. High species diversity (species richness and number of taxa) was recorded in the weeds substrate. The use of artificial substrate for sampling has shown to great significance in the bioassessment of unwadeable streams and rivers.