Chun, I.; Kang, H., and Lim, H.S., 2018. Revisiting Head Loss of the Perforated Wall with Vertical Slits. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1056–1060. Coconut Creek (Florida), ISSN 0749-0208.A theoretical analysis and hydraulic experiments were performed to investigate the head loss that occurs when a flow passes through a perforated wall with vertical slits. In the theoretical analysis, continuity and energy equations were applied to a control volume set near the perforated wall. A non-dimensional energy equation was then derived to calculate head loss for the given values of the ratio of upstream and downstream depths and a Froude number based on downstream depth and velocity. The hydraulic experiments were performed by varying flow condition and the opening ratio of perforated walls. The non-dimensional energy equation and experimental results were finally used to evaluate the accuracy of three existing formulas.