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Question

Can I do a fellowship in USA without residency or USMLE based on my previous experience in internal medicine, MRCP certificate?

technically it is possible to do a fellowship without doing residency.
but that is not common, and only in non accredited fellowships, or research based fellowships with limited/no clinical commitments. most accredited fellowships require US residency . (accredited fellowships are those that are accredited by ACGME, at the end of which you would be eligible for board certification in that subspeciality, non accredited fellowships do not give board eligibility)
These opportunities for fellowship before residency are unusual and hard to come by.
i am not sure you if you can do them without USMLE.

if the fellowship you want to get into has clinical component, then you will probably need a state licence, in most cases that usually requires doing USMLE, but there are alternative routes.

in general, people who go onto such fellowships usually have a lot of previous experience, come from large well known medical centers, and their transition is coordinated by their home instiution, and the american hospital/university where they want do the fellowship.
example, someone who completed his training in interventional cardiology in europe, comes to USA to do one year of advanced training coronary interventions, such a person usually applies through his own home country which has relations with the american center he wants to go to. such a person doesn't do a US residency, gets a temporary state licence (not sure if does USMLE steps or not), and comes does his fellowship and returns to his home country.

Now to practice, in most cases, such a person will usually have to do residency in USA, because to have a permanent licence that requires a USA residency in most cases. BUT there are exceptions in the rules, for people with exceptional skill/experience/background