Aim of our study was to assess functional outcome measured by modified Rankin scale (mRS) in patients that were treated with thrombolytic therapy-recombinant tissue plasminogen activator (rtPA) after acute ischemic stroke. The study included 100 participants that were treated after acute ischemic stroke. Analyzed parameters included: gender; age groups: age 54 and below (Groupup to-54), 55-64 (Group55-64), 65-74 (Group65-74), and 75 and above (Group75-up); cerebral blood flow (CBF) and cerebral blood volume (CBV). Considering time of rtPA administration, we analyzed 3 groups: between 1-2 hours from stroke onset (Time1-2h), 2-3 hours (Time2-3h) and 3-4.5 hours (Time3h-up). NIHSS scores were analyzed: NIHSS 1-at admission and NIHSS 2-at discharge from hospital; and mRS values: RANKIN 1-at admission and RANKIN 2-at discharge from hospital. There is significant reduction in NIHSS and mRS scores between two measurements for all groups of evaluated parameters. CBF, CBV and NIHSS values at admission significantly correlated with mRS scores at admission (p<0.01), as well as with mRS scores at discharge except for CBF where statistical significance was (p=0.019). Significantly lower values of NIHSS at admission (p<0.01), CBF values (p<0.01) and CBV values (p<0.01) are noticed in the group with mRS≤2. Early induction of rtPA treatment in patients with acute ischemic stroke within first 4.5 hours significantly increases positive treatment outcome in both genders and for all evaluated age groups. Favorable outcome (mRS≤2) at the time of discharge from hospital is significantly associated with lower NIHSS values at admission.