3,9-diazabicyclo[3.3.1]nonane derivatives, useful as monoamine neurotransmitter re-uptake inhibitors. Also, use of these compounds in a method for therapy and in pharmaceutical compositions comprising the compounds. The 3,9-diazabicyclo[3.3.1]nonane derivatives have the formula ##STR00001## wherein R.sup.a and R.sup.b are as described in the application. Also disclosed are stereoisomers and pharmaceutically acceptable salts of the compounds.