Closing the account will affect the "average age of revolving accounts." One factor in your credit score worthiness (I think 10%) is how long creditors have "trusted you" to have credit with them. You want that average to be 7 years or higher. So if you have 4 total credit cards that you've had open 20, 10, 5, and 1 years, the average age is 36/4= 9 years. If you cancel the 20 year card, it drops to 16/3=5.33 years. That would most likely drop your score 30 pts until the average age increases.