Waves generated by underwater landslides are studied in a physical laboratory model. A total of 102 laboratory tests were carried out. The experimental data measured generation, propagation and run-up of water waves. A wide range of effective parameters are considered in the experimental tests. Based on laboratory data, an empirical method is presented for prediction of impulse wave run-up caused by an underwater landslide in a dam reservoir. This method is developed using only the information about landslide geometry, initial submergence, water depth and sidewall slopes in the dam reservoir. The presented equation is successfully verified using laboratory-based and analytical equations from the literature. The equation is also applied in a real case study for a dam reservoir in Iran in which the impulse wave characteristics are available, and good reliability is obtained.