Abstract: The ecology and distribution of Inocybe bongardii (Weinm .) Quél. , I. leucoblema Kühn., I. perlata (Cooke) Sacc., and I. terrigena (Fr.) Kuyp. are treated on the basis of Finnish material. Though variable in colours, most of the material of I. perlata was found to fit excellently with Cooke’s original concept. A closer presentation is given of a study area in SW Finland where the calcareous bedrock and emissions from a limestone-processing factory have strongly affected the mycoflora. Heavy fall-out of chalk dust induces production of extremely large fruit bodies in Paxillus involutus (Batsch) Fr. Pluteus exiguus (Pat.) Sacc. and Inocybe amblyspora Kühn. are reported as new to Finland. In addition, many rare species are reported, whose occurrence is in most cases attributable to the calcareous bedrock and calcium fall-out, e.g. Chamaemyces fracidus (Fr.) Dank, Peziza succosa Berk. and Helvella oblongispora Harmaja.