The surface of polyethylene terephthalate films (the degree of crystallinity is 0.12-0.18) subjected to uniaxial drawing near the glass transition temperature of 353 K has been studied by electron microscopy and IR spectroscopy. Formation of a percolation cluster of densely packed particles, which is deformed as a whole entity, has been revealed in the films. The volume fraction of the cluster (Ω ≈ 0.5) and the degree of chain unfolding (β ≈ 0.7) at 343 K are independent of the drawing ratio in the region 1.1 ≤ λ ≤ 3.0. Near λ = 2.5, plane orientation of chains, for which the radius of particles in the amorphous phase is close to the radius of unperturbed coil, has been found. At 363 K, the cluster framework formation (Ω ≈ 0.6 and β ≈ 1) terminates near λ = 2.5. The drawing ratio λ ≥ 4 corresponds to microfibrils of chains with the parameters Ω ≈ 0.15 and β ≈ 1 and the fractal dimensionality D ≈ 1.