In this study, the effect of extraction methods on the properties of Althea officinalis l. (marshmallow) fibers was investigated. For this purpose, obtaining the fibers from stem was done by water and chemical extraction. After the extraction process, mechanical and thermal properties of althea fibers were investigated and morphological structure was examined. Crystallinity indexes (CI) of fibers were determined. Scanning electron microscopy results revealed that extraction of althea officinalis fibers by alkali boiling in 5% NaOH solution led to removal of surface impurities and also according to X-ray diffraction results, crystallinity index of fibers was improved by 14%. Chemically extracted fibers showed 37% higher tensile strength when compared to water extracted fibers. Density measurements revealed that chemically retted fibers have higher density. Also, Fourier Transform Infrared Spectroscopy analysis showed that chemical extraction caused change of chemical composition by decreasing and/or disappearing of some peaks which belong to hemicellulose and lignin.