An experimental study was carried Out to determine the effects of a coastal forest on tsunami run-up heights. The beach was built as a natural sandy beach at laboratory scale. The coastal forest model was constructed using artificial trees (FM-I) and cylindrical timber sticks (FM-II). Artificial trees were placed on a 1:5 slope in three different layouts: rectilinear, staggered. and dense rectilinear. It was shown that in the case when the trees were placed in the dense rectilinear pattern and close to the still water level (SWL), the run-up height was reduced by approximately 45% compared with the case without trees. After evaluation of the experimental results, the parameters that affect the run-up height were determined. These parameters were written as a dimensionless group using Buckingham's Pi theorem. An extensive regression analysis was carried out and equations proposed. Furthermore all, experiments were repeated with a slope of 1:3.5 to verify the proposed equations. The experimental results were compared with the results of the proposed equations, and it was shown a good agreement between the results. (C) 2008 Elsevier Ltd. All rights reserved.