Microlesion effect (MLE) is a commonly observed phenomenon after electrode insertion into the subthalamic nucleus (STN) for deep brain stimulation (DBS). The aim of this study was to determine the presence of the MLE in the early postoperative period and the relationship between MLE and STN DBS. 74 patients with Parkinson’s disease were included in this study. Motor symptoms were evaluated preoperatively, within 48 h after electrode implantation and at 6 months with United Parkinson’s Disease Rating Scale part III (UPDRS-III). According to the improvement level with MLE, all participants were stratified into three groups:(1) less than 20%;(2) 20–40%, and (3) more than 40% in OFF medication states. The degree of improvement in UPDRS-III with DBS ON for each MLE group was assessed at the 6-month follow-up. Regression analysis was applied for the evaluation of the relationship between MLE and improvement with DBS ON. Mean results in UPDRS-III with the MLE in ON and OFF medication states were 22.1±10.5 and 42.1±14 points, respectively. At the 6-month follow-up, with active stimulation, results tended to further ameliorate to 14.6 (59.4%) points in ON and 20.8 (55.3%) in OFF. Mean improvement in MLE groups were: 33.6% group 1, 47.5% group 2 and 61.4% group 3. Regression analysis revealed a positive correlation between the MLE and results at 6 months with DBS ON. Results proved the presence of MLE in the early postoperative period. Furthermore, a positive correlation between MLE and improvement degree with active stimulation was observed.