The macronuclear chromatin of Oxytrichia nova consists of chromatin fragments which are fully soluble in 0.2 mM EDTA and whose DNA length varies from 500-25 000 bp. The DNA migrates electrophoretically as a series of discrete bands, with specific genes present in only one or a few bands. The chromatin fragments are composed of nucleosomes and migrate electrophoretically in proportion to their DNA length. These results suggest schemes for the fractionation of undigested chromatin in order to enrich for specific genes, facilitating analysis of changes in chromatin structure associated with changes in gene expression.