While several types of mineral fibres, such as asbestos and erionite, are known to pose a carcinogenic hazard to humans, the evidence regarding other types of fibres, such as ceramic fibres and glasswool, is a matter of debate. This Consensus Report addresses the strengths, weaknesses and gaps in the present knowledge on fibre characterization, genotoxicity, cell proliferation and activation, and animal studies. The second part provides answers to specific questions on the relevance of mechanistic data from in-vitro and in-vitro assays in the assessment of the carcinogenic risk of fibres to humans. Finally, the relevance of mechanistic data in the evaluation of fibre carcinogenicity is discussed.