Exhibit 99.31 MBNA MASTER CREDIT CARD TRUST II SERIES 1999-B KEY PERFORMANCE FACTORS June 30, 2001 Expected B Maturity 3/16/09 Blended Coupon 5.9788% Excess Protection Level 3 Month Average 7.24% June, 2001 6.75% May, 2001 7.52% April, 2001 7.45% Cash Yield18.98% Investor Charge Offs 5.67% Base Rate 6.56% Over 30 Day Delinquency 4.78% Seller's Interest 8.00% Total Payment Rate14.15% Total Principal Balance$57,876,901,808.74 Investor Participation Amount$750,000,000.00 Seller Participation Amount$4,631,211,247.25