Rats received either ibotenic acid, electrolytic or sham lesions of the lateral hypothalamic area. Compared to sham operated rats, both lesion groups showed aphagia and adipsia following the lesion; this was less severe in the ibotenic acid lesioned rats. Once recovered, the ibotenic acid lesioned rats showed residual regulatory impairments in their compensatory responses to glucoprivation and to extracellular and intracellular dehydration. However, unlike the electrolytic lesioned rats, those with ibotenic acid lesions did not show akinesia and exhibited normal responses to both d-amphetamine and apomorphine. Ibotenic acid lesions resulted in extensive loss of cell bodies within the lateral hypothalamic area while sparing ascending dopamine neurones. The results are interpreted as suggesting that the lateral hypothalamic area and ascending dopamine neurones are components of a single system involved in the regulation of food and water intake.