Hyperthermia in patients with acute ischemic stroke is associated with poor outcome. Although previous studies have shown a negative effect on functional outcome, even in patients treated with intravenous recombinant tissue plasminogen activator (rt-PA), the effect on survival remains unclear. The aim of this study was to evaluate the association between the functional and survival prognosis and hyperthermia in patients with acute ischemic stroke treated with rt-PA. We studied 120 patients treated with rt-PA from 2306 consecutive Japanese patients with acute cerebral infarction at Aomori Prefectural Central Hospital between December 2009 and March 2017. We defined hyperthermia as ≥38°C within 72hours after rt-PA administration. Propensity score matching was used to compare 34 non-hyperthermia and hyperthermia patient pairs. Final modified Rankin Scale scores were higher in the hyperthermia group than in the non-hyperthermia group. In addition, the Kaplan-Meier model showed that the non-hyperthermia group had significantly better survival rates than the hyperthermia group (hazard ratio, 5.3; 95% confidence intervals, 1.2-24.8). Hyperthermia within 3days after rt-PA is associated with poor functional prognosis and survival outcome in patients with acute cerebral infarction.