The regional court in Oldenburg said in a statement that it would hear the proceedings against 41-year-old Niels Högel, accused of being the worst serial killer in German post-war history, which are expected to last until at least May.
The trial will take place in a large hall in the city to accommodate "120 co-plaintiffs, their 17 lawyers, interested members of the public and reporters".
Högel has admitted to injecting patients with drugs that cause heart failure or circulatory collapse so he could then try to revive them and, when successful, shine as a saviour before his medical peers and superiors.
In a case police have called "unique in the history of the German republic," he earlier testified that at times he acted out of "boredom", feeling euphoric when he managed to bring a patient back to life.
He was found guilty of six killings in two earlier trials, but investigators have pushed on with toxicology tests on hundreds more exhumed bodies.
In January, Oldenburg prosecutors said they had charged him with 97 additional murders on top of the six he has been convicted of, while saying toxicology tests did not find conclusive proof in three more cases.
Högel was jailed for life in 2015, but at the time it was suspected he had murdered many more patients, with investigators admitting they may never know the true number as some remains had been cremated.