An effective and efficient production method of narrow and thin strips made of steel, non-ferrous metals and their alloys is wire flattening in a ball rolling mill. In this device cylindrical rollers have been replaced with balls of diameter ca. 15 mm. Proper selection of deformation process parameters enables to obtain strips with the required geometrical characteristics. Experimental planning method was applied to evaluate the influence of flattening process technological parameters on strip geometrical features. Statistical analysis enabled to determine mathematical models of stainless steel 5XCrNi18-10 strips flattening. It was established that strip widening depends on ball roughness, draft applied, relation of wire diameter to ball diameter, back-tension stress. Strips flatness depends on draft applied. It was observed that strips feature uniform thickness over their width, parallel flat surfaces, narrow dimensional tolerance, high quality surface and naturally rounded edges.