Dear Rahul, NIOS studentsare eligible for AllMS. NIOS has an authority to take exam and certify its learners registered with it upto pre degree level courses. It is recognized by Government of India.

Any candidate is eligible to sit in AIIMS entrance exam if he/she has passed out class 12th board exam or any other exam equivalent to it from some recognized board or university. Candidates appearing for these exams are also eligible to take the entrance exam.

NIOS students are also eligible to take NEET 2019 as the clause which barred such students was removed by the High Court of Delhi. However, NTA has stated that eligibility depends on the final verdict of the special leave petitions filed by MCI. 

As long as you are 17 years old, have the required qualifying marks with subjects like Physics, Chemistry, Biology/Biotechnology, you are eligible to write NEET and AIMS.