Although it is true that walnuts are highly beneficial for people to eat, they are considered to be poisonous for rabbits because of some of the different things they contain, most notable phosphorus. This means that it is important to avoid feeding your rabbits walnuts or any nuts at all. While it is true that sometimes certain nuts are used in a rabbits diet, they are usually only fillers and should be given to them in moderation or not at all.
It is important to consider the fact that while some nuts are okay for rabbits to eat, others such as walnuts are not. They are toxic for rabbits and most other animals, causing problems that range from diarrhea to upset stomach.