Heat oven to 350°F (325°F for dark or nonstick cookie sheets). Mix cake mix, butter and egg in large bowl with spoon until dough forms (some dry mix will remain).
Shape dough into 1-inch balls. Mix sugar and cinnamon in small bowl. Roll balls in cinnamon-sugar mixture. Place about 2 inches apart on ungreased cookie sheet.
Bake 10 to 12 minutes or until set. Remove from cookie sheet to cooling rack.