This paper describes karst landforms observed in the northern Sinus Meridiani region of Mars, located between 1°20′–2°20′ N and 2°50′ W–1°E and covering an area of about 20,000km2.The karst is characterised by spectral signatures of mono- and poly-hydrated sulphates. A morphologic and morphometric survey of the study area was performed through an integrated analysis of 18 Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment. Four distinct karst terrains were observed in the study area; they resemble landforms in a variety of karst terrains on Earth. The Martian landforms are characterised by different doline depression features and display different kinds and degrees of karstification. This variation seems to indicate differences in relative karst susceptibility due to the solutional properties of the four units, and enables the use of the karst landforms as significant geomorphic markers to distinguish units compositionally and/or mineralogically in the Sinus Meridiani area. ► Four distinct karst terrains (KTs) are exposed at different stratigraphic levels throughout northern Sinus Meridiani. ► The KTs are characterised by different kinds and degrees of karstification. ► The differences among terrains as the result of different relative karst susceptibility. ► The karst landforms can be used as significant geomorphic markers.