Is PMI always required on low-down home loans?

A growing number of private lenders are loosening up their requirements for low-down-payment loans. But private mortgage insurance, or PMI, usually is required on loans with less than a 20 percent downpayment. The Homeowners Protection Act states PMI must be dropped on any loan originated after July 29, 1999 IF it has a 78 percent loan-to-value ratio.