A series of 12-(dialkylaminoalky1)-benzo [alphenothiazines has been synthesized for pharmacological evaluation. These compounds were obtained by thionation of various i\'- phenyl-a-naphthylamines and condensation of the resulting benzo [a]-phenothiazines with dialkylaminoalkyl chlorides using sodamide. Several N-acyl and sulfone derivatives of the benzo [a 1-phenothiazines also were prepared