Background: First aid is the treatment of any injury or sudden illness before professional medical help can be provided. The aim is to prevent the condition getting worse, ensuring fast recovery and preserving the precious human life. This study will contribute to identify the gap on Knowledge, attitude and practice of first aid among high schools and preparatory teachers of kolfe keranio Sub City in Addis Ababa, Ethiopia. Objective: - To assess knowledge, attitude and practice of first aid among high school and preparatory teachers in kolfe keranio Sub City, Addis Ababa, Ethiopia, 2017. Method: - A cross-sectional quantitative study was conducted from December 2016 to July 2017 in governmental high school and preparatory teachers of kolfe keranio Sub City in Addis Ababa City. The study was conducted on 3 samples from 8 selected high schools. Data was collected by using pretested, structured self-administer questionnaire consisting knowledge, attitude and practice questions. Result: -: About 163(95.9%) knew about first aid, their source of information was 62.2% from media, and poor knowledge about From a total respondents were poor knowledge about first aid 37(21.8%) of chocking, 39(22.9%) neck and back injury, 42(24.7%) fracture, 43(25.5%) human/animal bite,49(28.8%) swallowed poison, 61(35.9%) breathing difficulty, 65(38.2%) nose bleeding,74(43.5%) burning and 76(44.7%)epilepsy. Out of 74 (43.5%) who faced child with breathing difficulty, 42 (24.7%) has breath slowly and deeply, 39(22.9%) they encourage the student to calm down and sit quietly, 38 (22.4%) contacted responsible school authority and parent, while 26(15.3%) called ambulance. About 123(72.3%) had faced child with fainting. Eighty three (48.8%), of respondents kept the child on the flat position, 63 (37.1%), contacted responsible body, 55 (32.4%), loosen clothing around the neck and waist 41 (24.1%), had given nothing by mouth and 34(20.0%), called ambulance. Above half of the respondents (58.2%) felt good attitude towards giving and learning first aid. Most of the respondents (63.5%) strongly agreed that learning first aid is fair and few respondents (5.3%) strongly agreed that ministry of health give first aid training only few teachers. Conclusions: The study revealed practices knowledge and attitude toward first aid were limited, especially with cause, and management. Moreover, there were statistically significant differences between respondents with and without training of first aid. Keyword:-first aid KAP of high school teachers in kolfe keranio sub city