Problem Statement: Sports injuries are gradually increasing all over the world. School athletes are the first stepping stone in improving knowledge and skills in the community, therefore understanding and improving their knowledge is of great importance. Furthermore school athletes are the potential group that will make up the senior professional athletes population in the future. Prevention of injuries and proper first aid helps minimize injuries and reduce further complications. There for evaluation of the existing knowledge and practices of school athletes regarding injuries and their prevention is an essential exercise. This study will help to determine the extent of their knowledge in prevention of injuries and basic first aid. Objective: To identify the knowledge of prevention and rehabilitation of sports injuries among senior school athletes in Sri Lanka. Methods: A descriptive cross sectional study on senior school athletes in Colombo was done using a sample of 150 conveniently selected students, using a self-administered questionnaire with 10 close ended questions and analyzed using descriptive and analytical statistics. Ethical clearance was obtained from the Ethics Review Committee of the International Institute of Health Sciences, Sri Lanka. Results: Out of 150 participants, only 45 students have adequate knowledge of cryotherapy, 51 have basic knowledge of relieving cramps, 69.3% continue stretching though they have pain, 67.3% are unaware of proper bandaging protocols, 39.3% understand splinting and its uses and 26.7% are well informed on the necessity of CPR. Whereas, out of the 150 students, 80 students are aware of emergency wound care, 64% know standard first aid for ankle sprains, 75.3% are aware of the purpose of vapo-coolant spray, and 99.3% perform warmup exercises and 96% practice cool down exercises. Conclusions: Senior school athletes perform warm up and cool down exercises which is an integral part of injury prevention, but when considering basic first aid and post injury rehabilitation there are many aspects in which majority of the athletes are lacking in knowledge and training. Provision of knowledge on prevention of injuries and complications of injuries would help to upgrade their performance. It is vital to improve their knowledge in these areas to prevent further complications as well. Furthermore by considering all above factors it is necessary to establish a system to train and improve their knowledge serially. Additionally, policy changes may be needed to address this lack of knowledge in management of these injuries when they occur. Key words: Senior School Athletes, Sport Injuries, Prevention.