The Yucatan coastline has been experiencing beach erosion during the past few decades, reaching critical levels at some locations such as in Chelem beach located near the Progreso Pier. Despite this problem, only few studies have been devoted to investigate the role of coastal structures on explaining the high erosion rates. Therefore, the aim of this work is to evaluate the effects of the 6-km long Progreso Pier on the nearshore wave transformation and alongshore sediment transport in the study area. Field surveys were conducted in a monthly basis to measure the changes in the beach profiles. Furthermore, wave conditions were determined with an ADCP installed at 8 m water depth. Observations confirmed the high erosion trends(1m/year) that have produced coastal infrastructure damage and property loss along 10 km of coast. The wave measurements were employed as forcing on a third generation wave transformation model (MIKE 21 SW). Firstly, the numerical model is implemented in the study area for two different scenarios, with and without the Progreso Pier structure, in order to estimate the nearshore wave conditions. Subsequently, wave conditions predicted at 5 m water depth were employed for the estimation of longshore sediment transport in the study area. The modeling results showed that the pier acts as a large scale wave-sheltering structure that induces important longshore sediment transport gradients during mean wave conditions coming from the NE. On the other hand, during winter storms, when the dominant direction of the waves is from the NNW, the structure does not seem to play an important role on wave transformation into the study area. As a result, the Progreso Pier enhances beach erosion in the Chelem area by inducing longshore sediment transport gradients during mean wave climate and decreasing the capacity of waves to recover the summer beach profile.