Evidence that crystalline silica is associated with an increased rate of lung cancer led the International Agency for Research on Cancer to conclude in 1997 that crystalline silica is a known human carcinogen. In Israel too, crystalline silica is considered as such. The decision raised a debate in the scientific arena, and a few scientists have questioned the basis upon which causality was determined. We review the literature regarding the level of evidence of crystalline silica carcinogenicity.