A social worker had called the animal rescue services after the man said during a hospital visit that he was having trouble taking care of 20 rats at home and wanted to give them up.
But when they got there, the shocked animal protection workers discovered hundreds of the animals living in a flat completely given over to housing them.
The apartment had been filled with animal beds and sawdust for the rats. They had made nests in the drawers.
"Apparently the man tried to take care of the rats properly. But given the sheer number of rats he ended up out of his depth," Judith Brettmeister from the Munich shelter said in a statement.
“In all the drawers, in the bed frame and behind the cabinets were nests with babies – and they were all hungry.
"There were around 300 in total. A truly horrifying picture!”
Animal protection services took 20 rats - the maximum they are able to house - back to their shelter.
The rest of the rodents will be kept and fed in the two-bedroom flat until new owners can be found.
Any rat lovers in Munich should call 08031-9606869 if they want to take some - or a few - of the animals on.