From the results of an x-ray structural analysis of free dictysine it has been established that dictysine is an alkaloid of the denudatine type with an α, β, γ-triol system at C15, C16, and C20. The structures of the acetonides of dictysine and dehydrodictysine formed from dictysine and dehydrodictysine, respectively, in the process of separating the combined alkaloids, have been shown. © 1983 Plenum Publishing Corporation.