River Šujica is a karst abyss in western Herzegovina that flows through Krško Polje (Duvanjsko Polje) and the valley extension of the Šujica river (Šujicka Polje), making a composite valley. The Šujica river valley is rich in karst formations. The karst relief of this area is shaped by exogenous fluvial processes and karstification of carbonate rocks that build this area. The aim of this work was to investigate the geomorphological forms that occur along the Šujica river valley. The exogenous processes that led to the shaping of certain parts of the Šujica river course are described and determined. By using the existing literature and maps, the necessary data on previous research and the state of the terrain were collected. Field work and photo documentation were done in order to determine the current state and geomorphological features that are important for the researched area. Results show that the geomorphological features of the Šujica river valley were created under the influence of geological and hydrological factors that are characteristic of karst areas. The river Šujica is a typical karst sinkhole river and its flow depends on precipitation and groundwater. The entire valley of the river Šujica is rich in karst forms. The springs Veliki Stržanj and Mali Stržanj are overflow springs that dry up during the summer months. The river Šujica meanders due to the slope of the base of the valley, and by joining the meanders the river acquires a new flow, while in the winter months the valley of the river Šujica is being flooded due to the large amount of precipitation. The canyon of the river Šujica mostly has steep sides, and in some places even approximately perpendicular to the bottom of the river. The river also meanders through the Duvanjsko polje and, passing through a gentle canyon, plunges into the Kovača abyss, where it goes underground and reappears at the source of Ričina.