Among transplant centers in the US, the acceptance of kidneys from non-directed, altruistic donors is a relatively recent phenomenon, beginning in the late 1990's. Originally starting out as a handful each year, the number of nondirected donations has since increased to now represent over 3% of the annual living donor pool of transplanted kidneys. The psychosocial and functional outcomes of non-directed donors have been extensively studied, yet the demographic characteristics of these donors have largely escaped analysis on a national-level. We examined national UNOS data from the past 27 years to understand the demographic characteristics of non-directed donors by gender, ethnicity, citizenship status, UNOS region, and ABO blood type. In this analysis, we found that: non-directed donors are an increasingly important source of kidneys; non-directed donors have tended to be male, white, and US citizens; several UNOS regions (5, 7, and 9 in particular) are more prolific in performing non-directed donations than others; and non-directed donors are more likely to be of either ABO type O or A. Continued study of this population is needed to understand how these non-directed donor demographic characteristics may change over time.