Acute ischemic stroke (AIS) may experience early neurological deterioration (END) and have high risks of recurrent ischemic strokes (RIS), which are often associated with a poor outcome. Post-stroke prognosis is associated with autonomic status. Recently, studies showed that heart rate variability (HRV) is an early outcome predictor in acute stroke patients. The purpose of our study was to investigate association decreased HRV by fractal dimension (FD) with early END within 72 h of admission and 1-year RIS. In this study, we assessed autonomic function of ischemic stroke patients within 24 h from symptom onset by FD. Receiver operating characteristic (ROC) curve was utilized to determine the optimal cut point of FD for END and RIS. 516 patients (mean age 66.14 +/- 10.11) with acute ischemic stroke underwent a comprehensive clinical investigation and FD test. According to the data of FD, we investigated association with END within 72 h of admission and the 1-year RIS. ROC curve analysis shown that the optimal cut point of FD for END and RIS were FD <= 1.05 and FD <= 1.15 respectively. In fully adjusted models, there was an association between FD 5 1.05 and END (adjusted odds ratio, 2.64; 95% confidence interval, 1.55-4.49; P < 0.001), there was an association between FD < 1.15 and RIS (adjusted odds ratio,5.40; 95% confidence interval, 3.02-9.64; P < .001). These findings indicate that FD <= 1.05 and FD <= 1.15 were independently associated with increased risk of END and RIS respectively, which may have predictive value in END and RIS.