Objective: The efficacy of intravenous (IV) recombinant tissue plasminogen activator (rt-PA) therapy in the treatment of acute ischemic stroke (AIS) has been demonstrated in many studies and IV rt-PA therapy has been increasingly used all over the world. Early neurological deterioration (END) in AIS is common and potentially associated with a poor clinical outcome. The prevalence of END in AIS ranges from 13% to 37% in studies. The aim of this study is to determine the prevalence and risk factors of END in patients with AIS receiving IV rt-PA therapy. Materials and Methods: One hundred fifty seven patients who were given IV rt-PA treatment by Bursa Uludag University Faculty of Medicine, Department of Neurology between 01.01.2020 and 01.01.2021 were retrospectively included in this study. It was planned to determine the risk group by comparing patients with END with those without. Results: Age (p=0.023), serum glucose level (p=0.045), The National Institutes of Health Stroke score at discharge (p<0.01), Alberta Stroke Program Early CT (ASPECT) score (p<0.01) when clinical, radiological and demographic data associated with END were evaluated and, statistically significant correlation was found with the presence of major vessel occlusion (p=0.012), ischemic stroke due to cardioembolism (p=0.002), clinical outcome (p<0.001) and symptomatic intracerebral hemorrhage (p<0.001). When the significant variables associated with END were evaluated with binary logistic regression, the most significant variables were found to be age (p=0.006) and ASPECT score (p<0.001). Conclusion: The causes of END are multifactorial. The most associated risk factors were found to be advanced age and low ASPECT score. It was understood that the most common cause of END was the inability to perform mechanical thrombectomy for major vessel occlusion. Contrary to popular belief, the most common cause of END in patients with AIS who received IV rt-PA treatment was not considered to be symptomatic intracranial hemorrhage but to inadequate recanalization or late recanalization.