Background: The aim of this study is to determine if achievement of stable disease as a best response to HD IL-2 may improve survival outcomes. Recent data suggest that immunotherapy may improve survival even in those pts who do not experience objective responses (CR+PR). Methods: All sequential mRCC pts treated with HD IL-2 at the University of Utah (1988-2013) and University of Michigan (1997-2013) were included. Best responses to HD IL-2 were correlated with survival outcomes using landmark analysis at 2 months—the median time to first disease assessment. Results: A total of 391 pts (75% male; median age 55 yrs, range 13-77) were included and belonged to the following risk categories: 80 (20%) good, 251 (64%) intermediate, and 60 (15%) poor. A CR was identified in 35 (9%), PR in 39 (10%), SD in 125 (32%), progressive disease (PD) in 164 (42%), and not evaluable for response (NE) in 28 (7%) pts. Median OS for the favorable, intermediate and poor risk groups were 53.8 (p=0.0015 vs intermediate), 26.4 (p<0.0001 vs poor), and 12.2 (p<0.0001 vs favorable) months, respectively. Table shows correlation of response to survival. Conclusions: Stable disease as best response to HD IL-2 was achieved in 32% of pts and survival outcomes were not statistically different in these pts from those achieving PR, however significantly greater than those with PD. Stable disease is an important response criterion for treatment with HD IL-2, and may be discussed with the pts.