This study explores the potential effectiveness of olive mill wastewater (OMW) as an alternative to industrial surfactants in decreasing hydrophobicity in sandy soil. The OMW was obtained from a storage lagoon and characterized by high concentrations of short-chain fatty acids, mainly butyric, propionic and acetic, which contributed approximately to 1/3 of the wastewater organic load. It was applied diluted with freshwater (1:1) in an agricultural field in Greece affected by water repellency at a rate of 4 L/m2. OMW was found to be effective in decreasing soil water repellency, which suggests the potential of OMW to be used as a natural surfactant. The decrease in hydrophobicity was attributed to the fatty-acid related surface-active properties, enabling rapid penetration of OMW into the soil matrix, and the consequent enhancement of soil microbial activity that enables degradation of soil hydrophobic compounds.