ABSTRACT. – Among invertebrates living in estuarine ecosystems, shrimps are highly sought after as protein sources by humans and other organisms. Shrimps have a short life cycle and spend critical life stages in estuarine systems. Thus, changes in estuarine environmental parameters could influence shrimp distribution and abundance. This research aimed to determine ecological parameters that influence shrimp diversity in Merbok estuary, a mangrove hotspot area located in the northwest of Peninsular Malaysia. Six water quality parameters (temperature, salinity, conductivity, pH, turbidity, and dissolved oxygen) were recorded at three zones (upper, middle, and lower) along the estuary from September 2012 to March 2013. Shrimps were sampled using barrier and stake nets. Three water parameters showed significant differences among the sampling zones (p < 0.05) including salinity, conductivity, and pH. A total of nine species of shrimps from three families (Penaeidae, Palaemonidae, and Alpheidae) were identified, with Penaeus merguiensis being the dominant species in each zone. The species composition showed no significant differences among zones. The middle zone had the highest diversity index, attributed to its stable environmental condition, resulting from the mixture of polyhaline and mesohaline sea nutrient sources. Shrimp abundance was negatively correlated with temperature, conductivity, and pH, suggesting these as determinant factors for the assemblage.