Investigators in southwestern university town Tübingen said the three men aged between 49 and 67 were accused of "ending experiments on three monkeys too late and thereby causing the animals ongoing pain for a longer period."
In German law, animal cruelty can be punished with a sentence of up to three years in jail, depending on the seriousness of the crime.
SEE ALSO: VW hid 'devastating' results from diesel exhaust tests on monkeys
This case deals with experiments by the Max Planck Institute for Biological Cybernetics that were approved by authorities -- on the condition that the monkeys be killed if signs of suffering became apparent.
"Against the specified conditions for ending the experiment, (the accused) delayed in euthanising the animals, thereby causing significant and longer-lasting harm to their well-being," the prosecutors said.
"The accused should have recognized their obligation to intervene," they added.