After defining truly "neurotrophic" influences, and giving examples from the many studies of such influences on the somatomotor system, current research concerning sympathetic neurotrophic effects on the vascular bed is discussed. Tissue-culture studies have made it clear that, particularly in early growth phases, local trophic influences are quite important and interdependent between adrenergic neurons and vascular smooth muscle cells. Most experiments aimed at illustrating neurotrophic effects on vascular beds in vivo, however, seem to suggest the dominance of long-term adaptation processes inherent in the effector cells themselves which, particularly on sustained extrinsic activation however achieved, become increasingly mobilised. This is not to dispute the fact that truly neurotrophic influences seem to be superimposed, facilitating and modulating these essentially intrinsic mechanisms for long-term effector cell adaptation, but their relative importance is difficult to judge.