Prick pie shell with a fork and bake in preheated oven for 8 minutes, or until crust is lightly browned. Remove from oven and cool.
In a medium mixing bowl blend egg yolks and condensed milk. Stir in lemon juice. Heat this mixture in a double boiler, stirring constantly with a wooden spoon, until it thickens. Pour into piecrust and refrigerate at least 1 hour before serving.
