The catecholamines norepinephrine and epinephrine are used by the sympathetic nervous system to communicate with other organ systems, including the immune system. Adrenergic receptors on target cells bind these catecholamines and modulate the activity of the target cell. The beta 2-adrenergic receptor is the most abundantly expressed and best studied adrenergic receptor in the immune system. Here, I summarize data from our own laboratory and from others on the expression and possible function of alpha 1-adrenergic receptors in the immune system. alpha 1-Adrenergic receptor expression in the immune system can be regulated by glucocorticoids, by beta 2-adrenergic agonists, and by cytokines. In addition, the possible pathophysiological implications of the expression of alpha 1-adrenergic receptors on immune cells from arthritis patients are discussed.