THE central control of brown fat thermogenesis was evaluated in seventeen rats with moveable electrodes implanted in the ventromedial hypothalamus (VMH) and adjacent structures. Brown adipose tissue and core body temperatures were monitored in response to VMH stimulation; sites which elicited a rise in brown fat temperature were observed in the dorsomedial and anterior ventromedial hypothalamus, with BAT temperature profiles varying widely in duration and peak values. Given the complexity of BAT responses to endogenous VMH signals, these varied profiles may be mediated by dissimilar VMH signals, which remain to be characterized.