High-quality kitchen knives that are well-maintained can theoretically last a lifetime. However, knives of lower quality are at risk for rusting or their handles giving way. In this case, replace them immediately. Also make sure to sharpen your blades regularly, as often in our attempts to do culinary miracles with a blunt knife, we end up cutting ourselves. Lastly, spare the dishwasher and hand wash your most trusted chef's knife to increase its lifespan.