Vertical slender hydraulic structures such as sluices, navigation locks, or storm-surge barriers are often dynamically loaded by waves. For a safe and economic design, an accurate description of the wave loads is needed. A widely used formula for this purpose is the Goda–Takahashi wave load formula (GT). It was derived for the assessment of gravity-based caisson breakwaters. Due to its many advantages, the formula is also often employed for the assessment of vertical slender hydraulic structures, although its applicability to those type of structures was never fully demonstrated. This study provides insights in the applicability of GT for vertical slender hydraulic structures. This is done based on a literature review on the historical backgrounds of GT, and an investigation of several case-studies. In the case-studies, the equivalent-static wave loads for caisson breakwaters in scope of GT are compared with those for vertical slender hydraulic structures. The results show that GT can safely be applied for vertical slender hydraulic structures loaded by pulsating wave loads, but that systematic over- or under-estimations are expected for breaking or impact wave loads. For individual cases, differences up to 200% were obtained. These large over- or under-estimations underline the need for an improvement of the current design tools for vertical slender hydraulic structures loaded by breaking or impact wave loads.