The effects of neonatal nicotine and/or 6-hydroxydopamine (6-OH-DA) treatment on the postnatal development of central noradrenaline (NA) neurons have been investigated using neurochemical and histochemical techniques. Nicotine was found to produce an increase of 3H-NA uptake and endogenous NA in the cerebral cortex and pons-medulla, which was most pronounced at the age of one week. These parameters were normalized in the adult stage. Neonatal nicotine treatment was also found to partially counteract the 6-OH-DA induced alteraton of the development of the locus coeruleus NA system. The NA denervation produced by 6-OH-DA in the cerebral cortex and the spinal cord was thus counteracted by nicotine treatment. The results suggest that neonatal nicotine administration has a growth stimulatory effect on the early postnatal development of central NA neurons.