The manufacturer of your knife set should let you know on the packaging or website whether the knives are designed to be dishwasher safe or not. Most professional cooks and kitchen experts, however, will tell you that even if the knives are recommended for dishwashers, it is best to always wash the knives by hand. Dishwashers use a lot of water and do not dry efficiently, which can cause rust if the knives are not unloaded and stored right away.