This study set out to demonstrate the need for free clinics on a national level, to identify difference among types of free clinics in the US, to identify which services were commonly used, and to determine where else patients would seek care if not at the free clinics. Two separate, distinct surveys were sent out, one to free clinic directors and another to free clinic patients. Chi-squared tests, two tailed t-tests, and percentages were used to describe results and significant differences. 1,114 free clinics were identified in the US. 172 free clinics and 362 patients responded. Most clinics (44%) were independent. A mean of 4,310 annual visits was reported. Most patients used primary care (86%) and pharmacy (80%) services. If the free clinic did not exist, 24% would not seek care, 21% due to cost. Most would seek care at another free clinic (47%), or the emergency room (23%). Most patients were satisfied with their care at the free clinic (97%). Patient satisfaction correlated with use of primary care (P = 0.0143). Most patients (77%) reported greater satisfaction with the care they received at the free clinic than with their prior care. Free clinics provide primary care to a substantial number of uninsured and working poor. They provide an alternative to patients who might otherwise seek primary care in the emergency room. Even with reform of the national health care system, free clinics will provide primary care to millions of uninsured. How they will adapt to provide this care is yet to be seen.