The purpose of this research study is to assess the knowledge and achievement in Physics practical among higher secondary school students in Villupuram and Thiruvallur districts of Tamil Nadu State. Normative survey method was employed to collect the data from 270 students studying in higher secondary by adapting simple random sampling techniques. A self-constructed tool on knowledge in Physics practical Inventory was used in this research study. The objectives of the study aimed to find out the relationship between the knowledge and achievement in Physics practical and to find out the significant difference between knowledge in Physics practical. The major findings of the research study indicate that there exists a significant relationship between knowledge and achievement in Physics practical of higher secondary school students. Further it has been found that there exists significant difference between gender, medium and locality.