I had the same problem when I bought an old house. The mortar was starting to come out of some of the joints in the firebox. I asked exactly the same question to a mason (the kind that build brick walls & stuff) and he said that they use the same mortar in fireplaces as they do everywhere else.

My damage wasn't quite so bad as yours, so I used the premixed mortar patch in a caulking tube and just squirted it in. But if your bricks are coming out it may be worth mixing up some real mortar. Just make sure it's dry before starting a fire.

Hope this helps.

Hey, that really does help, Reef. Thank you! I even still have some mortar mix left from doing some repairs on my front steps, so I won't even have to spend a cent to do this home repair!

Ihave a question along the same lines I could use advice about.Our fireplace is in a room with hardwood flooring and the stuff that appears to be caulking in the groove between the bricks and hardwood needs to be filled in due to wear.What do people use for this?Our house is about 50yrs old.Any help appreciated,Thanks in advance.