Interest rate trends might be part of the reason, but another unspoken reason might be your credit report. Credit card companies look at it regularly. If you are late on other payments, or if you are becoming "maxed-out" on other cards...you might find yourself being charged more in interest, even on cards for which you have a perfect payment record. Another possibility: Identity theft or errors on your credit report. Your rates could be increasing through no fault of your own! It pays to check your credit report regularly.