Some 15,000 doctors across Germany are staging a walkout to press for higher pay and better working conditions, a union said on Monday.
Doctors at about 200 public clinics in most German states were on strike and 4,000 gathered for a protest in Munich, the Marburger Bund union said in a statement.
The walkout is scheduled to last all week, but the union stressed it could continue indefinitely if the towns and cities running the clinics don't make a better offer.
Minimum service is guaranteed in all hospitals. However, the union recommends that patients go to university clinics, private or church-run hospitals.
The negotiations over pay and working conditions broke down April 8. The employers are offering a 2.9 percent wage increase, as well as bonuses for night and standby duty, but doctors want a 5 percent raise and better pay for on-call services.
Marburger Bund's chairman, Rudolf Henke, said the walkout was not meant to harm patients.
"We want to strike against the employers, because the employers don't realize how precarious our situation is," German news agency DAPD quoted him as saying.
Henke hinted that it might be possible to reach an agreement even without having a full 5 percent salary increase.
The 700 clinics run by towns and cities represent about one-third of all German hospitals and employ 55,000 doctors.