It has been established that the DNA and H1 histone contents in aged coleoptile of 8-day-old etiolated wheat seedling are about 40 and 30%, respectively, lower than those in young seedlings. H1 histone in wheat seedlings is represented as six electrophoretically different subfractions. The ratios of H1 histone subfractions in wheat coleoptile and initial leaf are similar. In contrast to some animal cells, apoptosis in wheat coleoptile is not accompanied by changes in the set and ratios of H1 histone subfractions. Aging of coleoptiles is associated with a progressive diminution of the H1 histone and DNA contents. H1 histone/DNA ratio in aged coleoptile is 1.5-2-fold higher than that in the young organs. Therefore, the content of H1 histone in chromatin of coleoptile decreases with age more slowly than DNA content.