Six Long Island hospitals have earned top grades in a new report from medical organization LeapFrog Group.

The group analyzes how well hospitals prevent patient errors, infections, injuries and even drug mix-ups. The hospitals that received As are Mather Memorial and St. Charles hospitals in Port Jefferson, St. Francis in Roslyn, Winthrop-University Hospital in Mineola, Nassau University Medical Center in East Meadow and Mercy Medical Center in Rockville Centre.

Four other Long Island hospitals got Bs and 12 received Cs.