We've had customers ask us from time to time what might be wrong with their door lock if the key won't come out of the cylinder after trying to unlock the door. There are a number of reasons for this to happen, so I thought I'd mention some of the possibilities here - maybe someone could benefit. If your lock is brand new: Keyed cylinders are spring loaded with a series of pins that allow the cylinder to be turned if the correct key is inserted. There is a chance when the lock was re-keyed (assuming you had some door locks keyed alike or keyed to existing locks) the person who did the re-keying didn't get the pins completely seated in the key cylinder. This will sometimes allow the key to be inserted, but then difficult to remove. If this is the case, it will be better to have a locksmith take a look at it to get it keyed properly. If you have purchased the lock from DirectDoorHardware.com let us know and we can get the problem resolved. This doesn't happen very often, but we're humans and sometimes make mistakes. Luckily, this is a mistake that can be resolved. Before we go to the trouble of replacing or fixing the key cylinder, be sure to check one more thing... If you take the two halves of the lock off the door, on the inside of the keyed cylinder you will see a little set screw holding the cylinder in place and there is a thin piece of metal (referred to as a tail piece) connected to it. The tail piece connects the two halves of the lock so that when you turn the cylinder the mechanism is activated and unlocked/locked. Sometimes this set screw is not completely tightened (probably because the person rekeying the lock was in a hurry and just didn't get it tightened properly). Sometimes if you have an existing lock, this set screw can loosen over time. In either case, just give it a couple of turns to snug it up and then try working the door lock again. Keep in mind that every brand is slightly different so this might not be the fix for every brand. I snapped a quick picture back in the shop to illustrate what I am talking about - this is a Schlage lock shown. Many brands are assembled in a similar fashion. Schlage Door Lock - back view If Your Lock is Older: You could have a loose set screw inside the lock as I just described so you may want to check that first. Other possibilities might be: - Worn Cylinder/Pins In this case, there is no easy fix unless you have the proper tools and parts. I would suggest taking the lock into a locksmith as they will have the know how, tools and parts necessary to fix the issue. If possible, remove your lock and take it into a locksmithing shop. They will charge you a lot more if they have to come out to your house, usually it's fairly inexpensive if you just take the lock in. - Dirt and Grime Yep, could just be dirt and grime inside your keyed cylinder. Locks are installed with the keyed cylinder outside so over time dirt and grime can get their way into the lock.  You don't want to go overboard with lubricant. Try and find a good dry lubricant to start with, if that doesn't work you can use a little wd40 or something similar. Just squirt a little in the cylinder and work the key back and forth inside the cylinder to get the lubricant back into the pins. I've also heard you can insert a thin piece of wire along the bottom of the keyway to try and jar loose pins that may have jammed up. I haven't tried this myself so I couldn't tell you how successful it might be; and you could make things worse if you're not careful. But, i guess you could feel like James Bond picking a lock, so if you like that kind of thing, give it a go. Around here its just a few bucks to have the cylinder rekeyed, so I'd recommend just taking the lock into a locksmith and getting it done right. I just know i'd be the guy that monkeys with the cylinder for a couple of hours in attempt to make an old cylinder work a little better when it would have taken me 15 minutes to stop by a locksmith. And a few bucks later I'd have a new cylinder without issues. But, i like to save a buck just like the next guy so I'll leave that up to you.