Residual oil can be mobilized by reducing the interfacial tension between oil and water and/or by altering the wettability of the rock through surfactant flooding. Recently natural surfactants have been considered as opposite to synthetic surfactants due to environmental problems associated with synthetic surfactants. This work introduces a plant-based natural surfactant named Matricaria Chamomilla as an agent of reservoir rock wettability alteration. Qualitative and quantitative methods were used to measure rock samples' wettability. For this purpose, flotation wettability, separation wettability, and the pendant drop
method were used. The results show that Matricaria Chamomilla extract (MCE) changes the reservoir rock wettability to some degree equivalent to other natural surfactants. The highest wettability variation was observed at 12%wt MCE concentration with 28% change and 21% for critical micelle concentration (CMC) of 5.5%wt.