We present the analysis and the semiclassical quantization of the van der Waals states of ozone in the ground electronic state X (1)A(1). Progressions of these states dominate the spectrum of O-3 at threshold. Periodic orbits are used to perform assignment and quantization of the vibrational states. Semiclassical quantization is numerically accurate despite the fact that the classical phase space is chaotic while the nodal patterns of the quantum mechanical wave functions are regular. The lifetimes of recombination of the van der Waals states into the "normal" ozone are also discussed. (C) 2004 American Institute of Physics.