Vectors are living organisms that can transmit infectious diseases between human or from animals to humans. Mosquitoes are the best known disease vector. Vector borne diseases are characterized by the vector mediated movement of a microorganism such as a bacterium, virus or protozoa. A descriptive study, therefore, was undertaken to assess the knowledge of vector borne diseases among school age children in selected school, Chennai. The study samples consisted of 30 school age children were selected using probability random sampling techniques using lottery method. In order to assess their knowledge a self- structured questionnaire was developed. Self-made scoring system was used to categorize the participants as whether they have adequate knowledge, moderately adequate knowledge or inadequate knowledge on vector borne diseases. Results revealed that in post-test after structured teaching programme 24 (80%) of the school age children had adequate knowledge, 3(10%) had moderately adequate knowledge and, 3(10%) had inadequate knowledge about vector borne diseases. Structure teaching programme results majority of the school age children had adequate knowledge.