In Germany, most people are obliged by law to have health and nursing care insurance. As this obligation applies to both national as international students, exchange students are required to register with a statutory health insurance or a private health insurance provider. Usually, policies are offered to students at discounted fees. Proof of health and nursing care insurance that is in conformity with German laws and regulations is mandatory for all students in order to be enrolled at a German university. As a rule these certificates of vaild German regulated health and nursing care insurance bear the stamp "For submission to authorities".
For further reading on the topic, please visit the website of the German Academic Exchange Service:

PLEASE NOTE: International emergency travel insurance policies do not conform to German laws and regulations concerning student health and nursing care insurance as they only cover in case of emergency, and will not be accepted for enrollment.

How to give valid proof of health and nursing care insurance?

Students from countries in the EU:
Please send the completed  AOK-Form and a copy of your European Health Insurance Card (EHIC) via email to this email address:
Shortly after you will receive your valid certificate of health insurance for enrollment at UniBwM.

Students from non-EU countries:
Write an email including your personal information such as your name, date of birth, home country, and sex, to:
The AOK, a German insurance statutory insurance company, will varify your current health insurance policy. In case the AOK sends you an reply indicating that your health insurance cannot be accepted for enrollment at a German university, proceed as follows:
Complete the application form sent to you by AOK, and sign it. You will need a German address and a German bank account for payment. If those details are not available to you yet, please leave out as address and bank details can be given later after your arrival in Germany. Scan your filled out and signed application form to your AOK-adviser and you will receive your certificate of valid health and nursing care insurance required for enrollment soon after.

The "German Academic Exchange Service" offers an affordable combined health, accident and liability insurance package: