Novel therapies have transformed treatment for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), but how they have changed treatment for frail patients is unclear. Using Surveillance, Epidemiology, and End Results-Medicare data, we conducted a nested case-control analysis to evaluate the influence of frailty, measured with Function-Related Indicators (FRIs), on first-line treatment initiation. Four FRIs were positively associated and seven were negatively associated with treatment initiation, representing CLL/SLL symptoms and general frailty, respectively. During the chemoimmunotherapy era (2006-2013), patients with general frailty were significantly less likely to initiate treatment (aOR for 1 FRIs: 0.86, 95% CI 0.77-0.96; 2 FRIs: 0.83, 95% CI 0.70-0.98; ≥3 FRIs: 0.55, 95% CI 0.0.44-0.68 versus 0 FRIs). By 2019, this relationship diminished (p_interaction=0.031) with only the frailest patients less likely to initiate treatment (≥3 FRIs versus 0 aOR: 0.62, 95% CI: 0.41-0.99). This suggests disparities by frailty in first-line treatment initiation dissipated as novel therapies were approved.