  We summarize the status of our program of near-infrared adaptive optics
observations of ultracompact HII regions. By means of selected results we
demonstrate the usefulness of this technique for disentangling the complexity
of massive star-forming regions. The primary scientific aims of our study are
the identification of the ionizing stars, the characterization of the stellar
population, the clarification of the role of dust for the excitation of the HII
region and, last but not least, the search for circumstellar disks surrounding
high-mass stars. We present results obtained by adaptive optics observations
and additional measurements for G45.45+0.06, G5.89-0.39, and G309.92+0.48 to
illustrate our scientific objectives.
