For many families, the fear of adverse reactions or harm from vaccines outweighs concerns of the child's contracting the disease. Some families may still believe that the immunity derived from actually having the disease is superior to the immunity that develops in response to the receipt of a vaccine. Contracting some diseases, such as varicella, generally provides lifetime immunity. Hence from the above findings the present study was planned with the objective to assess parents’ knowledge, attitude and practice about immunization and to evaluate socio-demographic factors affecting immunization status of the children. The study was planned in the Department of Paediatrics in NMCH Patna Feb 2016 to July 2016. Total 50 child’s aged 1 month to 3 years were collected and presented as below. All the data was collected by standard interview methods. The interviews were conducted by specialists in paediatric infectious diseases, who also explained the medical terms involved. The vaccination status of the index children was determined by checking written vaccination records or on the basis of parental declarations if no such a card was available, and this was later compared with the digital records of the hospital. The current study collected the data about the knowledge about optional vaccination in childrens. The data collected from the present study suggest that insufficient knowledge of the parents calls for educational programs on paediatric immunization targeting the entire population with a special emphasis on maternal motivation and improving socio-economic status for the success of the Universal Immunization Programme in our country.