The influence of industrial pollution on the stem shape of Siberian spruce and fir trees was estimated in the Middle-Ural Copper Smelter vicinity (Revda, Sverdlovsk region, the southern taiga). As the pollution source is approached, the stem taper increases with a decreasing form factor. A statistically significant increase of the stem taper of Siberian spruce in the butt end (by 22.9%), the lower (35.7%), middle (18.0%) and upper (9.0%) parts of the stem is shown.