Maintaining compliance with medications is important in the management of patients with non-insulin-dependent diabetes mellitus. We examined correlates of medication compliance in 77 patients followed up prospectively for 24 weeks. Of the demographic, socioeconomic, and clinical variables examined, only older age and greater education were related to compliance. While statistically significant, the differences observed were small and unlikely to be useful to clinicians. Factors reflecting the process of care, including frequency of appointments, minutes spent with the provider, and patient satisfaction were not related to compliance. Symptoms associated with poor glucose control and fasting glucose levels were also not significantly related. The patient's report of his own compliance, however, was strongly associated with our independent measures of medication taking. We conclude that rather than attempting to predict compliance from sociodemographic characteristics, symptoms, or glucose values, the physician should directly inquire about medication taking in a nonthreatening manner.