When rats get into a house, chimneys and fireplaces are common nesting sites. Because rats are nocturnal, you might only see or hear them at night. If you start a fire in your fireplace and notice heavy smoke and a strong smell, it could be a rat nest burning in the chimney. Rats make nests by gathering debris into the narrow space of the flue of your fireplace. Rats sometimes carry disease and cause property damage, so getting them out of the fireplace is ideal. You can hire a pest removal specialist or do this yourself.
Call your local animal control or animal services department. If your city has this service, it would be listed in the phone book.
Ask if local services can send someone to remove the rats or if they can recommend someone who can. It might be free and available as a city service, or there might be costs. You might be referred to pest control services, or have the option of calling a specialist.
If you have to get the rats out yourself, set traps. Rat traps attract and catch rats, so if you have live rats in your fireplace or chimney, you can set traps on the floor of the fireplace or nearby. Go to a local hardware store to buy traps. Many types are available, some which kill rats and some which keep them alive. Choose the kind of trap you are comfortable with. Some stores sell rat poison next to the traps, but you can also use household foods as bait (like cheese or peanut butter) instead of poison. Do not use rat poison if you have children or pets. Be sure to follow all package directions carefully when setting the traps.
If your city does not have animal removal services or a clear policy about how to dispose of dead animals, you can dispose of it yourself by burying it or placing it into the trash. You can sweep up traps and dead rats using a broom and a dustpan, then seal it all in a trash bag. Keep trash bins outside and away from pets, and be sure to close them tightly. If you used live traps to catch the rats, release them outside. You can wear rubber gloves or gardening gloves to be cautious.
Keep rats out of the fireplace by getting the chimney cleaned professionally and installing a grate over the top of it. You can also prevent rats by getting rid of their food source inside. Deep clean all the tables, counters, food storage areas, cupboards, floors, dishes, and appliances. Don't leave food or crumbs out, and be sure all food is stored in sealed containers.