Superfine formulation of salmeterol.

A pharmaceutical aerosol formulation to be administered by pressurized metered dose inhalers which comprises as active ingredient salmeterol xinafoate or a stereoisomer thereof in a concentration between 0.005% and 0.15% w / v in solution in a system propellant, said propellant system for liquefied HFA propellant, from 5% to 22% being constituted w / w ethanol as a cosolvent, from 0.5% to 5% w / w water, a mineral acid and the formulation It has a pH between 2.5 and 5.5.