Abstract: The invention relates to a process for the production of morphologically uniform microcapsules that contain peptides, proteins or other water-soluble biologically active substances as active ingredients as well as microcapsules that are produced according to this process with a degree of concentration of between 3 to 30% by weight and a diameter ≦8 &mgr;m. According to the invention, biodegradable polymers are dissolved in a halogen-free solvent or solvent mixture, and the buffered active ingredient solution, which has a pH of between 6.0 to 8.0, is dispersed into this solution. Then, an aqueous solution that contains a surfactant (W/O/W-emulsion) is added to this W/O-emulsion, and the solvent is removed. The microcapsules that are produced with this process do not show any tendency toward agglomeration. The encapsulation efficiency of the process is approximately 90 to 95%.

Abstract: The invention relates to a process for the production of gaseous microparticles for ultrasonic diagnosis, whose wall material is built up from polyesters of &agr;-, &bgr;- or &ggr;- hydroxycarboxylic acids, particles that are produced according to this process, as well as their use in medical diagnosis.