The increasing interest in and importance of ectomycorrhizae make it more and more desirable that ectomycorrhizae taken from the soil can be identified. In this loose-leaf colour atlas, expected to contain 200—300 plates in the future, each mycorrhiza treated is illustrated on one plate with four good colour photographs and in addition on two plates with black-and-white microphotographs of the structures seen at the surface and in sections of the mycorrhizae. In this first fascicle 10 species are being analyzed, viz.: 2 Russulas, 4 Lactarius, 2 Dermocybes, and 2 Tricholomas. In the introductory part an identification key and a glossary are given.