Are you talking about those Ziploc bags? In any case, what were you planning on storing in it? If it's just your clothes, then I think it's fine in your carry-on luggage (assuming you can fit it in). However, if you're brining liquids, you're still required to place them in a "quart-size" bag and each container of liquid is only allowed to be up to 3 ounces. Read here for more information on
Airline Regulations.