Free and conjugated dopamine occurs in many tissues and fluids of mammals. We have used reversed phase liquid chromatography with electrochemical detection in sequence with an alumina adsorption procedure to separate and then detect amounts of free and conjugated dopamine in the major visceral organs and brain of the rat and mouse. We report those results here. Values for free and conjugated dopamine are given for all tissues studied. Conjugated DA was found in the rat kidney, liver and adrenal gland and in the kidney of the mouse. Those tissues which have a significant amount of conjugated dopamine will be studied further for the presence of dopamine sulfate.