Heat oven to 375°F. Stir together the peanut butter, sugar and egg in a large mixing bowl.
Roll dough into 1-inch balls. Put some sugar on a plate and roll balls in it to coat. Place 2 inches apart on ungreased cookie sheets.
Press each ball down with a fork to make a crisscross design. Bake for 10 minutes or until cookies just start to brown on the edges. Remove from the oven and let cool on wire racks.