From the 1st April 2010, if you have an accident in the Isle of Man you are not covered by the NHS for treatment
The long standing Reciprocal Healthcare Agreement between the NHS and the IOM healthcare system meant that UK residents travelling to IOM would be covered for any medical costs and the same for IOM residents travelling to the UK. The UK Government has ended this agreement effective from 1st April 2010. If you are thinking of going to the IOM TT this year read the Governments recommendations on the NHS website http://www.nhs.uk/nhsengland/healthcareabroad/countryguide/noneeacountries/pages/non-eeacountries.aspx