...You respond to an advertisement offering a free "trial" pair of pantyhose. To your surprise, you receive four pairs with a bill. ...You receive a pocket knife that you never ordered. Despite your objections, the company continues to send you notices demanding payment and threatening your credit rating.

What do you do when you receive merchandise that you didn’t order? According to the Federal Trade Commission, you don’t have to pay for it. Federal laws prohibit mailing unordered merchandise to consumers and then demanding payment.

Here are some questions and answers about dealing with unordered merchandise.

Q. Am I obligated to return or pay for merchandise I never ordered?

A. No. If you receive merchandise that you didn’t order, you have a legal right to keep it as a free gift.

Q. Must I notify the seller if I keep unordered merchandise without paying for it?

A. Although you have no legal obligation to notify the seller, you may write the seller and offer to return the merchandise, provided the seller pays for shipping and handling.

Q. Is there any merchandise that may be sent legally without my consent?

A. Yes. You may receive samples that are clearly marked free, and merchandise from charitable organizations asking for contributions. You may keep such shipments as free gifts.

Q. Is there any way to protect myself from shippers of unordered merchandise?

A. When you participate in sweepstakes or order goods advertised as "free," "trial," or "unusually low priced," be cautious. Read all the fine print to determine if you are joining a "club," with regular purchasing or notification obligations.Keep a copy of the advertisement or catalog that led you to place the order, too. This may make it easier to contact the company if a problem arises.

Q. Where can I go for help in dealing with unordered merchandise problems?

A. Always start by trying to resolve your dispute with the company. If this doesn’t work, contact your state or local consumer protection office, local U.S. Postal Inspector, or the Better Business Bureau in your area for help. The Direct Marketing Association also may be able to help you.