The output from a jet nebulizer was analyzed for aerosol profile, solution output, and delivery of albuterol at three different initial volume fills to determine the changes that occur during the course of nebulization. Increasing diluent volume led to significantly greater delivery of the albuterol initially placed in the nebulizer. Albuterol delivery from the nebulizer ceased completely following the onset of inconsistent nebulization (sputtering) as determined audibly and by laser particle analysis. Aerosol output rate declined by one-half within 20 s of the onset of sputtering. The albuterol concentration in the nebulizer solution increased significantly once the aerosol output declined. The weight of solution delivered as determined by change in weight of the nebulizer could not be fully accounted for as aerosol volume. It appeared that this discrepancy represented loss of water by evaporation. Aerosolization past the point of initial jet nebulizer sputtering is unproductive.