Based on experimental and epidemiological data findings presented here, as well as on data of other investigators, the authors conclude that a wide interindividual variability of susceptibility to silicosis is a real phenomenon. This susceptibility depends on both intrinsic features of the host and the influence of many environmental factors. The effect of any such factor is realized at different stages of silicosis pathogenesis and in close interrelation with the influence of other factors. The necessity of multifactorial analysis is stressed, and an example of such analysis is presented.