Models of smoke kinetics and lung dynamics of inhaled particles are discussed and compared with the available literature on mainstream and sidestream smoke particles. The literature search reveals a dearth of reliable information on the deposition of inhaled particulate tobacco smoke components in the human lung. Scanty results on mainstream smoke range from unexpectedly high deposits to values in line with predictions of conventional mathematical deposition models confirmed in tests with stable aerosols. For sidestream smoke, only one well-described experimental result is available. It is in agreement with established deposition probabilities. Experimental and theoretical estimates of relative particle deposition in the human lung range from some 10% for sidestream smoke particles to more than 80% for mainstream aerosol. This indicates a need for more, and better, experimental data.