Introduction: IV thrombolysis is a proven treatment for acute ischemic stroke (AIS), but it is still underutilized in real-world clinical practice. Using a nationwide multicenter stroke registry, we aimed to determine whether there are significant trends in the rate of IV thrombolysis in different patient populations. Methods: This study assessed patients with AIS or transient ischemic attack (TIA) registered prospectively in the Clinical Research Center for Stroke-Korea (CRCS-K) registry between 2013 and 2022. Trends in IV thrombolysis rate were respectively analyzed for all patients (cohort 1), patients who arrived at the hospital within 4.5 hours of onset (cohort 2), and patients potentially eligible for IV thrombolysis (cohort 3), using joinpoint regression analysis. Trends in IV thrombolysis rates in cohorts 1-3 were further investigated using generalized linear mixed-effects models adjusted for patient characteristics and accounting for hospital heterogeneity. Results: A total of 76535 patients were included in the analysis. The mean age of the patients increased from 67.3 to 69.8 years, and the median time from onset to hospital arrival increased over the 10-year period. During the study period, proportion of patients arriving at the hospital within 4.5 hours of onset and the proportion of patients potentially eligible for IV thrombolysis decreased, especially after 2016. IV thrombolysis rates significantly declined over the 10-year period in cohorts 1-3, with a pronounced decrease in the treatment rate in potentially IV thrombolysis eligible patients from 2013 to 2016 (average annual percent change [95% CI] -4.55% [-5.66% to -3.46%] in cohort 1; -2.63% [-3.95% to -1.34%] in cohort 2; -1.33% [-2.06% to -0.49%] in cohort 3). In the multivariable model, patients who arrived in 2022 were less likely to receive IV thrombolysis compared to patients who arrived in 2013 (adjusted odds ratio [95% CI], 0.83 [0.75 - 0.93]). Conclusions: Utilization of IV thrombolysis has declined over the decade in Korea, even accounting for the decline in the number of patients who are candidates for the treatment. Urgent interventions to increase IV thrombolysis rates are needed to improve acute stroke care.