The study was developed in Qbda. Ancha, Qbda. Limón, Chilibre, and Chilibrillo, during period September 1999 – May 2000, in order to describe the macroinvertebrates community associated to leaf packs, and to establish relationships among physico-chemical and biological variables. A 25m long study site was established in each stream, where physical measurements (width, depth, and discharge), two water samples, and three leaf packs were taken monthly. Sites were diferent in terms of discharge, SS, PO4, NH4, and biological variables. A number of 12,639 macroinvertebrates were collected, representing 107 taxa, including 49 insect families, 8 taxa of Mollusca, and one or two groups of Turbellaria, Chelicerata, Crustacea, Hirudinea, Oligochaeta and Nematoda. Most abundant taxa were Smicridea, Leptohyphes, and Chimarra. Functional feeding groups seem to show possible relationship between water quality and some insects that use leaf packs as substrate.