Objectives : To explore the type and frequency of short term reactions, de Qi associated with acupuncture treatment and to determine the incidence of adverse events following acupuncture in Korea. Subjects and methods : This study is a retrospective and cross-sectional survey of patient reports. 1095 subjects, 585 of out-patients of the Oriental Medicine of Stroke & Neurological Disorders Center, East-West NEO Medical Center of Kyunghee University and 510 of out-patients of the Department of Cardiovascular & Neurologic Diseases (Stoke Center), Hospital of Oriental Medicine, Kyunghee Medical Center, from June through November of 2006, who had acupuncture, gave informed consent and completed one survey form. On this form, patients were asked to report short term acupuncture reactions, de Qi, patient satisfaction measurement (using VAS), and adverse events relating to acupuncture treatment. The acupuncturists of this study are Korean Medicine Doctors (KMD) who had worked as practitioners for 3-30 years or more. Results : The average age of the 1095 subjects was 58 years old. Positive short term acupuncture reactions after treatment were reported by 878 (80.2%), negative short term acupuncture reactions by 75 (6.8%) and no reactions were reported by 142 (13.0%). The most common positive short term acupuncture reactions were feeling 'relaxed', 472 (43.1%), followed by feeling 'less pain' 90 (8.2%), 'energized' 16 ( 1.5%), 'tingling' 16 (1.5%), 'heat feeling or Cold feeling' 10 (0.9%), and others 274 (25.0%), respectively. Negative short term acupuncture reactions were feeling 'pain' 37 (3.4%), tiredness 24 (2.2%), dizziness 9 (0.8%), and others 5 (0.2%), respectively. Traditionally described needling sensations of de Qi refer to a patient's response to distention, pulling, soreness, heaviness, numbness. 39.7% of subjects reported de Qi during needling, experiencing 'distention' 333 (30.4%), 'soreness' 52 (4.7%), 'pulling' 22 (2.0%), 'heaviness' 18 (1.6%), and 'numbness' 10 (0.9%) respectively. Positive short term acupuncture reactions and de Qi rate were the highest in the less than 40 years group (83/96 86.5%, 50/96 52.1%). No acupuncture reactions were highly seen in the over 70 years old group (31/187, 16.6%). Patient satisfaction level using VAS was a comparatively high $72.9{\pm}19.9$. Adverse events were only bleeding in 92 (8.4%) of the total subjects. High sensitive acupoints were 95 points as GV26 (54 times), LI4 (54 times), ST36 (53 times), GB20 (37 times), HT8(34 times), LV3 (29 times), SI3 (29 times), and LI11 (27 times) in order. Main impressions were stroke patients 430 (16.9%), headache 185 (16.9%), hypertension 97 (8.9%), and dizziness 85 (7.8%). Conclusions : Although 8 different Korean Medicine Doctors participated in this research, we obtained similar results from each. There were no significantly different results between the two hospitals. Short term acupuncture reactions and de Qi were most related to age. Except for bleeding there were no adverse events relating to acupuncture treatment in this study. We consider acupuncture treatment as very safe depending on practitioners. Positive short term acupuncture reactions after treatment were 12 times higher than negative short term acupuncture reactions. Subjects were comparatively satisfied with acupuncture treatment.