If used incorrectly, occasionally. If the marker leaks, blot the tip dry with a napkin. The marker will work like new. Only prime the marker when new or if the marker stops writing. Do not shake the marker without its cap firmly secured. Store tip-side-up. When using the marker every day, you do not need to shake the marker every day. Excessive shaking, priming, and storing tip-side-down may cause leaking.