A method for obtaining an elongate polysaccharide element, in particular a chitosan thread, includes extruding a hydroalcoholic extrusible solution containing a polyalcohol of said polysaccharide through an extrusion die, coagulating the extruded solution by neutralization, and at least one operation of removing the polyalcohol. The ratio of water to polyalcohol in the extrusible solution is determined such as to obtain in the elongate element a polysaccharide with the crystalline structure thereof mainly in the form of an anhydrous allomorph. Since the polysaccharide used to prepare the extrusible solution has a weight-average molar mass Mw0, the polysaccharide in the elongate element obtained preferably has a weight-average molar mass Mw1 comprised between Mw0 and 0.7 Mw0. Since the purpose is to obtain a chitosan thread, the latter has properties of mechanical strength and flexibility that allow the thread to be tied into overhand knots and to be woven without breaking.