We have previously demonstrated that spermidine is required for proliferation and differentiation of murine Friend erythroleukemia (MEL) cells. Other studies have indicated that inhibition of MEL differentiation by dexamethasone (DEX) and 12-0-tetradecanoylphorbol-13-acetate (TPA) is reversed by the addition of exogenous polyamines. The present work has thus monitored the requirements of polyamines for induction of MEL hemoglobin synthesis by dimethyl sulfoxide. The results demonstrate that spermidine depletion inhibits induction of both heme synthesis and transcription of alpha- and beta-globin mRNA. In contrast, the results also demonstrate that polyamines are not involved in the inhibition of MEL differentiation by DEX and TPA. Thus, spermidine is required at a transcription level for induction of MEL hemoglobin synthesis, but DEX and TPA act by mechanisms other than polyamine depletion.