(+)-Naloxone was prepared in 26% overall yield in eight steps from (+)-7-bromodihydrocodeinone dimethyl ketal by a synthesis which excluded enantiomeric contamination. (+)-Naloxone was examined in three assay systems and found to have no more than 1/1000(-1)/10 000th the activity of (-)-naloxone; it can, thus, serve to test the stereospecificity of the biochemical and pharmacological actions of (-)-naloxone.