Abstract: A tubular container for centrifugal separation suited for easy separation of a relatively small amount of the phase having an intermediate specific gravity from the heaviest and lightest phases. The container has a first section defining a bottom chamber of a certain volume for containing therein the heaviest phase, a second section contiguous to the first section and defining an intermediate chamber for containing therein the phase having the intermediate specific gravity, and a third section contiguous to the second section and defining an upper chamber for containing therein the lightest phase. The diameter of said second section is smaller than the diameters of the first and third sections.