In Ehrlich ascites tumour cell nuclei ledakrin (1-nitro-9/3'-dimethylpropyloamine/acridine-2 HCl) induces condensation and margination of chromatin, compaction and segregation of nucleolar components and conglomeration of chromatin granule clusters. Localization of DNA in nuclei of the cells labelled with 3H-thymidine and subsequently treated with ledakrin is studied using high-resolution autoradiography. Besides strong labelling of condensed chromatin some radioactivity is associated with IG conglomerations. Possible role of chromatin fibrils in the formation of conglomerations of IG is discussed.