Six derivatives of adenosine were examined on their pharmacological actions and whole body distribution in relation to their radioprotective action. They all caused a large drop in blood pressure and slowdown of pules rats. Respiration rate was slightly decreased with concomitant overbreathing. Labeled compounds of two of these adenosine derivatives, N-(14C-2-hydroxyethyl) adenosine and N(35S-2-mercaptoethyl) adenosine, were synthesized. Whole body autoradiographic study in mice showed a significant accumulation of the compounds in liver, spleen, intestinal mucosa and bone marrow.