An account is given on the development of a purely mechanical Micro Spray Pump (MSP) which is capable of delivering aqueous drug solutions to the respiratory tract. The MSP is working with two phase flows which were investigated in respect of different nozzle designs. In-vitro, deposition characteristics of two solutions, food dye and salbutamol sulphate, at different dosage levels and various flow rates were determined; respirable fractions up to 21% were found. Recoveries above 88% were achieved. A theoretical flow model was employed to understand the effect of a spacer. In-vivo experiments where a Technetium (99mTc) labeled isotonic saline solution was nebulized by the MSP showed that bronchial deposites averaged 10%. The MSP prototype proved to be a feasible alternative non-propellant driven device to deliver drugs to the respiratory tract.