The ubiquitous casein kinase II (CKII) has been shown to accumulate in the cell nuclear compartment, following exposure to extracellular growth stimuli (O. Filhol et al., Biochemistry, 1990, 29, 9928-9936). The aim of the present study was to examine whether intracellular polyamines, whose levels are increased under similar conditions, could be related to this process. It is shown that (i) CKII accumulates in nuclei of adrenocortical cells exposed to their trophic hormone ACTH; (ii) this CKII nuclear translocation is concomitant with an increase in nuclear polyamine content resulting from ACTH-induced polyamine synthesis; (iii) selective inhibition of polyamine biosynthesis by DFMO results in the inhibition of both ACTH-induced cellular polyamine increase and CKII nuclear accumulation. These observations suggest that polyamines may be examined as intracellular messengers in the regulation of CKII activity and subcellular distribution in the cell response to growth factors and trophic hormones.