You must ensure that your health insurance ("Krankenversicherung") provides sufficient coverage abroad or that you arrange sufficient coverage elsewhere. 

The immigration authorities of the state in which you wish to work will normally require evidence of adequate health insurance cover as a condition for issuing a work permit. Please first check whether your insurance company in Germany will cover the medical and hospital treatment costs incurred during your stay abroad. The insurance company must then confirm in writing that your insurance cover is also valid abroad. If you do not have sufficient insurance cover (i.e. that does not cover serious illness and accidents abroad), you should ask the organisation awarding the fellowship or your host institution about information regarding suitable insurance companies.

There are only a few countries in which foreign workers are exempt from compulsory health insurance schemes. Whether you need foreign health insurance depends on your destination. If you plan to go to another country within the European Union, you likely may benefit from a number of simplifications and standardisations thanks to the European integration process. Please see the "Special Case: Health Insurance Holders in the EU, EEA and Switzerland" page for further details.

The following applies for other countries: Most countries have a statutory health insurance system that essentially any employed person is required to pay into, even if they are from abroad. However, exceptions may exist if a Social Security Agreement  has been reached with Germany, which means that the German health insurance regulations continue to apply.

If this is the case, your German health insurance or pension scheme provider will confirm this using form number 1 (or 101). Based on form number 1 (or 101), you continue to be subject to German health insurance regulations and are therefore exempt from the health insurance scheme of the country in which you intend to work. If you have not been issued with form number 1 (or 101), you will (as an employed person) be subject to the compulsory health insurance regulations of the country in which you intend to work.

Persons employed in Germany deployed abroad are entitled to all benefits granted within the German health insurance from their employer in the form of benefits in kind, i.e. to the value of the costs due abroad and not only to the value of fictive treatment provided in Germany, Section 17, Paragraph 1 German Social Security Code V (SGB V).