The Slano blato landslide is one of the oldest, largest and most active landslides in Slovenia, with a volume of more than one million cubic metres. In its recent history, a large earthflow was triggered in November 2000, and in summer 2003 a dry crust was observed on the surface of the earthflow for the first time, indicating the start of the drying out and de-saturation of the earthflow masses. In order to better understand the suction variation inside the earthflow body and the drying–wetting processes, three representative locations were instrumented with suction probes in 2007. Soil samples were also taken for laboratory determination of the soil water retention curve and volumetric behaviour during drying. The results of the 6 year monitoring program showed that only prolonged wet periods change the suction in the earthflow body. A sudden decrease in suction was observed in the case of depths of up to 1.0 m during rainfall events in high suction periods, indicating the propagation of desiccation cracks to the depth of the suction probes. From the results of the monitoring and of corresponding laboratory measurements it was concluded that suction variation is not the result of de-saturation, but rather of volume deformation (i.e. shrinkage).