Abstract: In spun fleeces of thermoplastics in which the filaments are in approximately random arrangement, which fleeces have been strengthened by needle-punching and which have a higher tensile strength in one direction than in the direction at right angles thereto, the said tensile strengths are approximated to one another by stretching the fleece by 20 to 200% of the original length, in the direction of the lower tensile strength, at a temperature which is 85.degree. to 25.degree. C. below the crystallite melting point, while either maintaining the length in the direction at right angles to the stretching direction, or changing it, beforehand or simultaneously, by an amount within the range of .+-.10% of the original length.