Several aspects of quality of care at one chain of freestanding ambulatory health care walk-in centers were evaluated. Those areas for which data were available--medical record review, physician credentials, and patient satisfaction--suggest that for primary acute episodic care, HSMMI walk-in centers provided care comparable to that which would have been received in traditional health care settings. In fact, HSMMI offices were found to be similar in organizational structure and appeared very much like private physicians' offices in management, staffing, patient flow, and physician performance. The corporation's QA program evolved from a series of informal managers' meetings (in 1986), to a detailed and structured program involving a CEO and regional medical directors by the end of 1990. The exact way in which HSMMI's new emphasis on formal quality-of-care assessment and assurance will affect patient care will be seen as the program fully matures. The issue of the proper relationship between money and medicine remains a problem. As health services organizations are increasingly influenced by market forces and consumers have ever-higher expectations, patients and physicians alike want to be sure that high-quality health care remains the first priority. Although this is an issue for all providers, it is much more visible in proprietary offices, making physicians as well as the public uneasy. For this reason, HSMMI's burden of proof regarding quality may be higher--particularly within the medical community--than the burden on traditional private practice physicians.(ABSTRACT TRUNCATED AT 250 WORDS)